User:Phol ende wodan/YANI

DEPRECATION WARNING: This page has been deprecated in favor of the new YANI Archive. This page will no longer be updated and will probably eventually be removed.

This page is an list of YANIs I've come up with. Feel free to use and implement them as you see fit.

This page used to contain an archival list of YANIs from IRC; I've moved it to User:Phol ende wodan/YANI/IRC archive. Though this page contains plenty of ideas I've proposed on IRC that didn't get input from others.

Monsters

New monsters

Rat king (not the SLASH'EM unique Rat King), based on the real-life rat king. It is a r, not much faster than a rock mole, but has several bite attacks (possibly scaling the amount by monster level). Each bite has a small chance of conferring disease. Its level corresponds to the number of entangled rats, so a slashing attack could sometimes cut off one rat, which then appears on the floor as a new rat, and makes the rat king lose a level.
New demon lord who spellcasts, favoring touch of death and summon nasties. However, the only thing it summons and gates in are incubi and succubi.
New demon lord with a fire attack comparable to Asmodeus' cold attack (this is actually already implemented, but is unused). It seems weird that no demon lords are really associated with fire.
Demon lord who has no real special abilities, but has a very, very high physical damage output.
Silver golem.
Slime mold as a new F monster, which is guaranteed to drop a slime mold comestible on death.
Mosquitoes, a class a monster which also uses an AD_DRHP attack.
Pixies, an n monster that can hide under objects. Chatting to them will make them say "Hey! Listen!" as an Ocarina of Time reference.
Some sort of late-game nymph monster that steals items. Helps mitigate an underlying issue: some of the early-game threats like stealing are completely absent in the late game, with no particular reason for that being the case.
Ice golems (Unnethack already has these.)
Monster that steals your intrinsic invisibility (but only that, unlike gremlins).
Monster or attack that un-erosionproofs gear, not very common.
Arch-foocubi which do the same seduction as regular foocubi, but the random number they choose has a higher average than a foocubus' 1-35, so the chance of a bad effect is greater and raising stats will not do as much. Perhaps rnd(35) + 25. They are also more grabby than regular foocubi, and will steal jewelry if you have insufficient gold.
Dementors, W monsters that have some sort of blinding, despair-inducing attack. Lawful aligned. If you become completely incapacitated by one, they suck out your soul for an instadeath.
Itinerant merchants who, if chatted with, offer one of several non-renewable trades. Generate on stairs, path to the opposite stairs, and once they reach them they disappear forever from the game. Generated with the requisite inventory to make all their trades. Always peaceful. Tougher than shopkeepers, since they have to defend themselves out in the dungeon. If you kill one, no more will ever spawn.
Wyverns and/or wyrms that share the D glyph but don't have breath attacks.
Darkness elemental: darkens squares it moves through (removing the lit state, if the square was permanently lit beforehand).
Will-o-the-wisps: y monsters that spawn individually, leave no corpse, and have no attacks except a passive blindness attack. They emit light radius 0 so you can see them, but no surrounding squares, across a dark area. Not infravisible, and could have teleportitis to replicate their folkloric effect of suddenly vanishing. Spawn rarely in swamp rooms and may not spawn at all in a lit area. Most importantly, they have a special AI that causes them to avoid the player and orbit around treasure (occasionally) or around hazards like monsters or traps (commonly).
Burrowing monsters that don't actually dig out tunnels (or phase), but instead move through solid rock non-destructively. They only move through solid rock; they won't move into wall spaces or move into corridors or rooms of their own volition.
Fairies, a n monster similar to pixies: very small, flying, capable of hiding under objects. However, they are lawfully aligned and (?) always generated peaceful. If you #chat to a non-hostile fairy, it will heal you a moderate amount (as in the Legend of Zelda) and become cancelled.
Bumblebee, very like a killer bee, but its poison sting is worse. However, when it stings you, it becomes cancelled and can't sting you again; a cancelled bumblebee additionally loses 1 HP per turn.
Carpenter ant, which eats wooden items on the floor and can dig, but only on wooden terrain (doors, trees).
Satyr, a h monster that is either chaotic or lawful (either could fit), are always male, generate with booze frequently, and chase after any nymphs nearby (who flee or teleport from them). Appear in the Ranger quest frequently.
Bookworm, a w monster that eats books (they end up in its stomach/inventory and aren't destroyed). Levels up, gaining power and speed, for each book it eats (higher level books give it more power), eventually gaining more attacks. Possibly can also eat scrolls. Initializes as having already eaten a few books.
Fire nymph, n, which normally only spawn in Gehennom and are noticeably stronger than other nymphs. Have two steal attacks which burn any items stolen, and also a fire attack. They also explode into fire when killed.
Goldfish, a ; monster that is level 0, always generates peaceful and has no attacks. The purpose of having it is for flavoring special levels, especially quests.

Monster behavior

Aggravate monster from a ring (and only from that) gives pets a special behavior: as they are aggravated, they will attack enemies with no regard to their current HP or the enemy's level, basically ignoring the checks that exist.
Green slimes have an engulfing attack that guarantees to start the sliming process (assuming the player isn't unchanging, on fire, etc).
Small mimics (but not large or giant ones) can mimic the floor, looking like nothing in the same way a trapper or lurker above does.
Wandering hostile priests of Moloch occasionally generate in Gehennom.
Hostile conflict angels don't appear on the Astral Plane any longer, but A and @ are now immune to conflict on the Astral Plane.
Add a knockback attack and a monster that can use it. Getting knocked back into a wall deals some extra damage, and getting knocked back into water or lava has predictable effects.
Asmodeus and Baalzebub have a chance of re-appearing hostile to their levels (not a certainty; if they always came back there'd be no reason not to kill them off) when the player is on the way back up with the Amulet. Flavor-wise, this is because the player only paid for safe passage down, and now the player has their coveted Amulet.
Monsters may spawn on the upstairs or downstairs in sight of the player; this is easily flavored as them coming in from other floors. If the monster selected spawns in groups, it picks somewhere that isn't the stairs, though.
Intrinsic cold resistance only halves damage from Asmodeus' cold attack unless you are extrinsically protected by a ring of cold resistance.
When riding a non-flying, non-swimming steed, give a warning by making the steed stop and "shy away" before riding into water. Only allow this if you use the m command or the steed has already shied away once. But it's not very fair or realistic to have the steed instadrown under you.
Nazgul's sleep gas acts as a beam, not a ray, and therefore cannot be reflected.
Water nymphs may create a pool on their spot when killed. Items they stole from the player fall into it, of course.
"You hear the splashing of a naiad" may happen if there is a water nymph on the level at all.
New hallucinatory monsters: "floatin' guy", "combinatorial explosion", "violent gem", "Ignatz", "wish parser", "technical difficulty"
Storm giants have active and passive shock attacks. Not sure why they don't actually have anything to do with shock currently.
Sandestins, when they can see the player, examine the player's worn equipment and try to shapechange into something that the player appears to be vulnerable to.
Disintegration rays have a small (on the order of 5% or 10%) chance of destroying the player's reflection source instead of reflecting. This terminates the ray, so the player can't get hit twice by it.
If ents exist, chopping down a tree angers any ents on the level.
Chameleons randomly select a monster of up to (level difficulty + N) when shapechanging, not any monster ever.
Vampires drain levels much less than they currently do, or not at all; instead they use a bite with an AD_DRHP damage type, which drains your HP and heals theirs by the amount of damage done. Possibly give vampires one AD_DRHP attack but let vampire lords keep one AD_DRHP and one AD_DRLI.
Change covetous warping so it only works for demon lords on their lair levels, and then they can only warp back into their lair.
Zombies and possibly mummies have a new sound MS_GROAN instead of MS_SILENT. This would not do anything at the moment except give you "The zombie groans." when #chatted to.
Hippocrates, being sick and frail, does not start moving around when you first #chat to him. You cannot use his throne or chest until you complete the quest and heal him with the Staff of Aesculapius. Before this, if you wish to kill him, he is extremely easy to kill and should be easily one-shottable.
If a shrieker summons a purple worm with its shriek, check for difficulty first. If purple worms would be out of difficulty, generate a baby purple worm instead.
After you finish the Priest quest, Nalzok may appear once more, randomly in Gehennom, since you didn't actually kill him the first time, just banish him.
Some monsters' corpses, like rats, have a chance of conferring FoodPois when eaten, regardless of whether they are rotten.
If you light up the square of a sleeping undead (through carrying some lit object or casting light), the monster wakes up.
Undead in Sunsword's light radius will flee.
A sessile invisible monster with a nasty passive attack.
Add a "summoned" flag to any monster that is created by you through magical means. Such monsters grant no experience when killed.
A b-class monster which is a shapechanger and may transform into any P, b or j monster.
Elemental giants and Lord Surtur get elemental attacks corresponding to what kind of giant they are.
Black lights have a radius 1 area of darkness instead of light.
New monster strategies: completely sessile, stays around a fixed point like altar priests do but with a variable radius, and repeatedly select a random point on the map and pathfind to it.
If you attack a spellcasting monster that currently has maximum energy, it may cast a counterspell to ward off your attack.
Rock piercers instakill stone golems, glass piercers instakill glass golems and iron piercers instakill iron golems.
Demon and undead pets move reluctantly over blessed items.
Purple worms eat corpses in 1 turn, because they can eat the monster in 1 turn so why not the corpse?
Purple worms going "Burrrrp!" wake up nearby monsters.
Trappers' digestion happens much more quickly than purple worms, on a shorter timer.
Any G that generate inside the wine cellar secret area in the Gnome King's Wine Cellar are automatically hostile regardless of race or alignment.
Quest monster generation gets reduced to almost nothing once the nemesis is defeated. Alternatively, monster spawn rate in the quest is very, very low, and more monsters are generated with the level.
Gelatinous cubes can eat doors in their path.
Increase the difficulty of werecreatures, to compensate both for their lycanthropy and that they are capable of summoning many monsters of equivalent difficulty.
Most d and f monsters can be pacified, but not tamed, by throwing appropriate food at them (they will eat it, so you can't reuse the same food item).
When chameleons polymorph, they retain their same number of hit dice and hitpoints. So while you may be facing a minotaur or an arch-lich, it's a very fragile one.
Shopkeepers charge a hefty fee for digging pits in their floor, hundreds or thousands of zorkmids. The shopkeeper will warn you when you start digging.
Dragons' alignments are adjusted so that the values actually matter (at the least, yellow should be very lawful, gray should be pure neutral, and black should be very chaotic), and are not specified as M2_HOSTILE anymore so that they can rarely be generated peaceful. Perhaps more interestingly, their difficulties should be varied.
You can pay the Oracle to tell you the depth at which various branches split off from the main dungeon. These are then recorded in your #overview.
Monsters that spawn in groups are regarded by the monster-generation function as having a higher difficulty than they actually do.
Mimics are very likely to mimic chests, instead of random items most of the time.
All Riders have intrinsic player-style MR, but summon insects and summon nasties don't work on the Astral Plane.
Purple worms' "Burrrrp!" wakes nearby monsters.
New monster behavior flag M2_CLIMB or M3_CLIMB: added to monsters that are natural climbers (spiders, ants, most Y) and with effects like being able to get out of a pit in one turn, or who can climb up ladders without having hands.
Whirly engulfing monsters have a random chance of causing dizziness (stunning) every turn you are engulfed.
MZ_GIGANTIC monsters cannot enter any space that has nonwalkable terrain on at least one pair of opposite sides in any direction (like a doorway). MZ_HUGE monsters cannot enter any space that has nonwalkable terrain on 2 (or maybe 3) pairs of opposite sides (like a corridor).
Skeletons can spawn in places that aren't Orcus-town.
Balrogs have a fire attack.
Golems do not regenerate hit points, and healing spells do not work on them.
Pets are not stealthy by default, and wake up sleeping monsters just like the player does.
When the Wizard of Yendor has the real Amulet, he gets an infinite mana pool to cast from, or otherwise his magic becomes more powerful.
The crossaligned high priests on Astral are hostile.
Consorting with foocubi abuses Wisdom.
Whenever a zombie steps over a zombie corpse, it revives.
Killer bees' evasiveness is so high that a player should still be missing them a lot even in the late game. To compensate for this, their HD is reduced to 1. However, area of effect attacks always tend to hit monsters regardless of evasiveness, so are still useful against them.
Ghosts cannot be touched with most items, or the player's body, similar to shades (probably blessed + silver objects would suffice). They don't need to have an amazing AC anymore because of this.
Foocubi can be pacified or tamed by throwing a ring of adornment at them.
The proper way to make late-game elemental damage matter is to give late-game enemies elemental attacks with large enough damage to matter, which don't care about reflection.
Fleeing monsters may randomly get a few bonus movement points.
In the absence of monster hallucination being implemented, make them stunned whenever they would become hallucinating.
Unicorns can only be tamed/ridden if you have never consorted with a foocubus.
Throwing treats at other types of animals, like most non-domestic d or f, will make them devour it, and will often pacify them and occasionally tame them.
Piranhas and other sea monsters' AT_BITE attacks can only hit you if you're actually in the water, in a water space next to them.
Monsters lacking hands can only carry up to a certain weight maximum which depends on their size. The player, if polymorphed, gets this as carrying capacity.
Scale M1_CONCEAL with monster size, so that larger monsters with M1_CONCEAL can hide behind objects of a sufficiently high weight or those that are oc_big.
Intelligent pets don't eat shapeshifter corpses unless you give it to them.
Dwarves don't go within two spaces of a tree if they can help it. (This is an Order of the Stick reference.)
Archons emit light.
Soldiers and watchmen can be tamed by throwing gold at them. In order to make them tame, you must give them over a certain initial amount X, which will give 1 point of tameness, and giving them additional gold will increase tameness by 1 for every Y gold. Tameness steadily declines over time, removing Y gold from their inventory each time it drops by a point. Should tameness drop to zero, they become hostile. Chatting with them while tame will give you a clue about how tame they are: they will either talk about how they're going to spend all their money, or wonder when the next payment is coming, or threaten you for more gold, depending on the amount of tameness. Normal magical taming methods do not work on them (as currently happens).
Croesus is generated with 2 random amulets and 5 random rings (bling) in inventory.
Change rothes' AT_CLAW attacks to AT_BUTT (also probably do this for most q).
If a monster has horns, AT_BUTT attacks deal extra damage.
When the hero observes a fox take fire damage, print a YAFM about Mozilla Firefox or automatically name the fox "Mozilla".
You can tame your own ghosts by #chatting to them. This doesn't work all the time; perhaps the ghost otherwise just doesn't react or hostilely touches you instead. It also requires disabling the player's ability to rename ghosts.
All monsters of class W get the PASSWALL monster flag, allowing them to phase.
When something infects you with lycanthropy, the infector and all of its summoned monsters become peaceful.
When you ride a clinging monster like a wumpus, you get a TDTTOE about all the blood going to your head.
Priests object to you locking the door of their temple, and will unlock it with a wand of opening if you try. If they cannot for some reason, they get angry.
Spiders can spin webs as they move along (cave spiders with less frequency than giant spiders.) This chance is boosted if they move into a doorway or choke point.
Give Lord Surtur fire attacks, since he doesn't actually use any.
Assuming a shallow water behavior is implemented: all H should use the shallow water behavior even when walking through deep water.
Spiders have an attack that wraps you in a web (using sticky behavior?) or creates a web on your square and traps you in it, so you can't move. Perhaps a to-hit penalty should be assessed when you are stuck like this.
More randomization or unpredictability in foocubus results so a player can't be nearly or actually guaranteed of a good result by having a certain amount of Int and Cha.
Change how drowning attacks work, by making them pull you into a water square that is adjacent to both you and the attacker, and then sticking to you so you can't move out of the water. This requires that the hero be allowed to survive (with a suffocation timer) underwater for several turns without magical breathing. If there are no mutually adjacent water squares, the attacker can't use their drowning attack.
Rock moles (and other tunneling monsters?) can't eat through wooden doors.
Unicorns (possibly only coaligned) can be tamed by throwing them a specific gemstone, which is deterministic for each individual unicorn and is random. Or else keep it simple and make it a low-ish chance per gem thrown.
Since monsters implicitly know the layout of the dungeon, they can use a secret door like a normal door (which converts it into a normal door in the process).
On March 15th, your first minor consultation from the Oracle will always be "Beware the Ides of March."
Shopkeepers can be cancelled (only artificially). When cancelled, they won't buy or sell any items. They will still react to theft, but they can't be paid and they don't offer any money or claim ownership of items you drop in their shop.
Monsters that are MZ_HUGE or larger block line-of-sight a la the dnethack giant turtle.
If you kill a grown-up form of a monster, all equal or lesser forms of it that see it die turn hostile even if they were formerly peaceful and the monster you killed was hostile.
Golems will pick up (and add to their body?) any item made up of the same material as them.
Telling a vault guard you are Croesus or an alias might fail, depending on your Charisma. If it fails, the guard becomes hostile.
The first major consultation from the Oracle is always free, and subsequent ones are always cheaper than they are now.
Stalker corpses don't confer see invisible anymore, and have their odds of conferring invisibility decreased from 100%.
Fire vortices uniquely among whirly engulfers don't make your lamp go out when they engulf you; they keep it ignited.
It should be possible to have monsters that are sessile but still get "movement points" to make active attacks. Lichens and spotted jellies are two good examples of monsters that could be like that.
When a monster is crushed in a drawbridge, its inventory might be dropped instead of totally destroyed.
When you kill a jabberwock while hallucinating, give the message "Oh frabjous day! Callooh! Callay!"
Fog clouds block line of sight.
Monsters that hide under objects can also hide under or behind various types of terrain, such as sinks, ladders, thrones, and headstones.
When a monster that hides under objects moves from one hiding spot to another, there's a very low chance that you notice it and it becomes unhidden. This chance is boosted by higher Wisdom, and having searching provides a boost.
Vampires can only regenerate while standing on top of a gravestone or in a graveyard. (Ideally, they could only regenerate in a coffin, but nethack lacks those.)
A pet will only eat a polymorphing corpse if its tameness is very low. Otherwise it will avoid it.
Same-sex foocubi will use an amulet of change on themselves as an offensive item.
Give a YAFM for telling a vault guard your name is Spartacus.
When werefoo summon help, the help appears at random locations on the level, out of sight if possible, not around the player.
Djinni released from bottles and water demons released from fountains don't care about beatitude or depth for giving a wish; instead they will give the hero a wish if the hero is intimidating enough. "Intimidation" is based on stats like Charisma and XL, and the chance of successfully intimidating them increases as they do. Djinni from lamps are not affected by these rules.
Monsters that generate with weapons should automatically be wielding those weapons, unless they generate asleep or peaceful. The player shouldn't get a free turn while they use theirs to wield the weapon (notable with player monsters on Astral).
Give Croesus a gold-stealing attack in addition to the regular attacks he has now.
When a vampire is killed in shapeshifted form and reincarnates in its normal form, it comes back at half health. Due to this, vampire AI sometimes chooses to stay in normal form at full health.
Nazgul have limited gating ability. Every time one lands a hit on you, there is a small chance that another nazgul spawns somewhere else on the level.
Gnomes that generate outside the Mines generate carrying one or two random gems.
Fiery monsters and possibly some demons get healed by fire traps and will deliberately jump onto them in order to heal up.
Cancelled monsters can quaff potions of restore ability to uncancel themselves.
Acid blobs will always be able to be generated by create monster sources, even if 120 of them have been born.
Monsters will throw random (non-cockatrice) eggs at you. If they hit you, your Cha is temporarily reduced sharply, until either you get hit by or immersed in water or until you #wipe with a towel.
Ants can dig tunnels in rock (slowly).
When you trigger the Kops, it doesn't immediately summon massive swarms of them all at once. Instead, it triggers an effect that lasts 50+d50 turns, which causes one Kop to spawn on the upstairs and downstairs each turn, and occasionally on random spaces. Reconciling with the angry shopkeeper cancels the remaining duration of the effect and vanishes any existing Kops on the level.
Increase piercer damage by a lot, make the piercer hit ignore AC so that it hits most of the time, and make helms not count for much against a falling piercer.
Remove the monster spell destroy armor, and instead allow them to read destroy armor scrolls at you offensively.
Monsters will only pick up projectile ammo if they are carrying an appropriate launcher; they will otherwise ignore it. (Darts and daggers and things that are thrown directly always get picked up.)
Hostile monsters zap wands of make invisible at fellow hostile monsters, allowing monsters that can't usually use items to become invisible.
The hostile angels created on the Astral Plane by wearing conflict are immune to conflict.
Some monsters, a subset of item-using monsters, can't read scrolls even though they can use all other items. Trolls and some orcs would be in this set (possibly even allow some members of a species to read and some not to, based on their m_id.)
Ghouls eat rotten corpses they find on the ground.
Instead of actually becoming any random monster, chameleons choose any random monster type to display as, but their attacks and stats remain those of a chameleon.
Monsters that divide/split must find a space adjacent to the splitting monster that is safe for the new monster to be on; if no space exists, the split doesn't happen.
When a monster is about to wake up from sleeping or unfreeze from paralysis and you can see it, give a message to that effect.
Dwarf and gnome kings will never pick up worthless glass, flint stones, or loadstones on the ground (they continue to pick up all valuable gems).
Add another negative foocubus result: you get a headache, which gives 10-20 points of HP damage.
Some angels generate with a harp. A fraction of those that do get a magic harp; the rest get mundane ones.
Monster speed system that tries to keep all the good qualities of 3.6.1 while also not letting randomization make monsters super fast or super slow: add a 16 bit int to the monst struct, and every 12 turns set (speed % 12) of them to 1. Then on each turn, the monster gets (speed / 12) moves, plus 1 if the bit for that turn is 1. This 12-turn cycle would need to be phase shifted randomly per monster (probably using hashing based on monster ID) so that you can't move-count based on the turn clock.
The Wizard will only cast Double Trouble if he has already been killed at least once.
Famine's hungering attack takes the maximum of his current 40-80 nutrition and a large fraction (1/2 to 3/4) of your current nutrition.
If you try to buy a high level spellbook in a shop while outwardly looking unqualified (low XL, low Int, Barbarian), the shopkeeper raises an eyebrow and condescendingly asks you if you're sure you can read it.
A monster flag that designates that its inventory is actually the contents of its stomach and is therefore not stealable, nor usable by the monster. Gelatinous cubes, rock moles, purple worms, and the bookworm above should get this flag.
Monsters only spend their turns on picking up items and equipping weapons and armor if they don't think you are close by. So when fighting a mob through a choke point, you don't get free hits on every monster that steps onto the pile of dropped loot and begins to equip themselves from it.
Croesus is able to displace other monsters, because he's the king.
Mimics can mimic other pieces of furniture like sinks and thrones. (They can already mimic doors and stairs.)
Vault guards grudge leprechauns.
Vampires grudge werewolves.
Mindless undead are immune to every form of fear effect, including scare monster.
When a monster picks up an item owned by a shop, its base price is deducted from any gold they're carrying and gets transferred to the shopkeeper. If they're short on cash, they don't have to make up the difference at all.
Zombies can't open doors, but if there is a critical mass of 5 or more adjacent zombies on one side of a door, they can bust it down.
Undead caught in a flash of light (from cameras or just from casting an area light spell) get awakened if they were asleep or confused (with a chance that decreases at higher levels) if already awake.
Shriekers caught in a flash of light shriek (however, this should only come from non-renewable sources to avoid being able to use them to farm monsters, or possibly this shriek should be unable to summon monsters.)
Assuming player monsters can steal the Amulet from you: with 50% chance, they may instead steal an imitation amulet you are carrying in main inventory. (It's a 50% chance of stealing a fake regardless of how many you are carrying).
Aligned priests can sometimes generate with 1-2 holy water instead of 1-2 of their spellbooks. Moloch priests will get unholy water rather than holy.
Assuming monster casting has been expanded somehow to include ally buffing: an orc shaman can generate with a group of other orcs.
If a monster would receive a teleport item but the level is non-teleport, don't give it to them.
Monsters can defensively zap you with a wand of teleportation if you are not on a non-teleport level.
Demon gating happens more or in greater quantity when in Gehennom, and less often outside Gehennom.
Werecreatures, including the player, never change into their beast form during new moon. (If a level is restored with the creature in beast form during new moon, it will be forced into normal form.)
Ants (or locusts, if implemented) can eat food off the ground, and they create more of themselves when they do, proportional to the nutrition consumed.
Monsters can wear amulets of ESP. This allows them to know your exact location when you are within the telepathy radius.
Monsters can drink potions of booze as a defensive item, but only when fleeing. It cancels their fleeing and confuses them.
Ants can dig and tunnel out corridors when there is an anthole on the level, eventually turning the whole level into an anthole-like network of corridors. The tunneling AI prioritizes connecting up existing corridors rather than just destroying rock indiscriminately.
Allow monsters to hallucinate (mostly from the same sources that cause the player to hallucinate, e.g. exploding black light). Hallucinating monsters will, after choosing a target, refuse to attack it 90% of the time (because it sees it as a fellow hostile monster). They also will not pathfind to items on the floor because they cannot see them clearly.
Shopkeepers won't buy wands from you if they are empty.
When a light explodes, all monsters adjacent to it are affected equally.
G-class monsters will pick up tools if they wander onto them. (They won't specifically seek them out and pathfind to them though).
Shopkeepers will buy identified glass for the same few zorkmids they will buy it unidentified, rather than refusing to buy it.
Trappers and lurkers above are mindless so they're not trivial to find and avoid with telepathy.
If a peaceful unicorn sees you wielding or applying a unicorn horn, it gets angry.
Flavor the Dark One as either a servant/lieutenant of the Wizard, or someone ambitious who wants to attack him.
Not all vampires are capable of shapechanging. Some of them will remain in their ordinary form. A smaller fraction of vampire lords is the same.
Gas spores, because they are volatile, always have exactly 1 HP, regardless of their level or HD.
Eating a rust monster while polymorphed into an iron golem is instantly fatal to your polyform.

Monster death-drops

Adult female dragons drop eggs (more so than the usual oviparous drop odds)
Killer bees occasionally drop lumps of royal jelly
Skeletons may drop skeleton keys
Rock moles and other item-eating monsters drop any gold or gems they have eaten (digesting them can't be a fast process), or they destroy 10% of all gold they eat and have a 10% chance to destroy any other items they eat; otherwise those items will be placed in the mole's inventory.
Air elementals drop some rocks (and "sticks" - the occasional wand of nothing?) which is the debris you have been pummeled with. (Also makes Air a little less difficult to cross if you haven't got a levitation source.)
Corpses dropped by mummies are always cursed.
Straw golems have a smallish chance of dropping a T-shirt.
Corpses dropped by aligned priests or priest player monsters are always blessed.
Queen bees drop a few killer bee eggs.

Objects

New objects

Add "candelabrum" as a new randomly generated tool. It can hold 3 candles and gives a light radius of 2 with one candle, 3 with two candles, and 4 with three candles. Its material is brass. The Candelabrum of Invocation's unidentified description is now "ornate candelabrum".
Brass knuckles: gauntlet-slot armor, increases bare hands and martial arts damage based on enchantment, but does NOT provide any AC bonus.
Potion of training: gives you a temporary multiplier to your experience point gains (lasts for the next N monsters, not the next N turns)
Armor of training: has no AC, but gives you a small multiplier to your experience point gains permanently. (This has been added to FIQhack as an object property.)
Characters with at least Basic in sling can do something (use a touchstone? flint stone? any gray stone?) to break rocks into slingshot, which weigh 1 and have comparable to-hit and damage to flint stones. Slingshot may be weapon-class instead of rock-class. The higher the sling skill, the more shot that one can get out of a single rock. There should also be rare silver rocks, which can be broken into silver shot.
Blowguns, which can be used as a launcher for darts. (Cavemen can thematically use these.)
Chain whips and silver chain whips, which use whip skill.
A cloak of flying.
Sunglasses, an eye slot tool that reduces the chance of being blinded from a bright light to 20%. They lower the chance of successfully searching. Tourists start with a pair of sunglasses equipped.
Lemons, a comestible that deals 1 point of damage when eaten unless acid resistant and exercises Constitution. If you are killed by eating a lemon, the death reason is "killed by citric acid".
Party hat, a conical hat which increases Cha by 1 if uncursed, 2 if blessed, and decreases it by 1 if cursed.
Whetstones, imported from SLASH'EM, but with some additional effects:
- Cursed whetstones either weld themselves to your hand or have a chance of breaking a weapon rubbed on them.
- Blessed whetstones can uncurse a cursed weapon rubbed on them, but at the cost of removing the whetstone's blessing.
- Rubbing rocks on a whetstone will break them into slingshot.
Tomatoes, a type of comestible that you can throw at monsters to decrease their charisma (if they had charisma).
Wand of identify: a non-directional wand that will always identify one item when zapped.
Wand of charging: non-directional wand that uncursed-charges an item in inventory. Will explode if someone tries to recharge it. Cannot be used to blessed-identify things in any way.
Scroll of repair: replacement for the scroll of food detection; uncursed repairs all levels of erosion on an item of the player's choice; a blessed scroll repairs all erosion in the player's inventory; cursed scroll attempts to erode one random item in inventory 1d3 times. If confused and non-cursed, will erosionproof an item of the player's choice; if confused and cursed, will remove erosionproofing from a random item and then erode it 1d3 times. The scroll of enchant weapon retains its confused effect of erosionproofing a weapon, but it no longer erosionproofs non-weapons or repairs the weapon. Enchant weapon scrolls are also made much less common, with the probability dumped into the scroll of repair instead.
Amulet of drain resistance, which also gives immunity to death magic. Useful if monsters casting drain life are implemented.
New randomized appearances: "starry spellbook", "iridescent potion", "creamy potion",
Some consumable object that lets you freshen a corpse (for eating or sacrifice short of undead turning.
In variants that limit the number of pets you can have, an amulet that allows you to have more pets than you normally can.
Bodkin arrows that have heavyshot (from DynaHack): instead of multishooting, they deal double or triple damage depending on how many you would have multishot otherwise.
Jars, which are like tins except made of glass. Generate quite often as chest contents. Possibly, can discern what is in the jar just by looking at it.
Woolen shirt, shirt-slot armor which gives zero AC but cold resistance.
Potion of smoke bomb: makes you choke/vomit when quaffed. Intended to be thrown; where it shatters, most of the surrounding terrain will be transformed into cloud.
Scroll of create magic item, which attempts to generate a magical item. If the scroll is blessed, you can choose the object class; if cursed, the object will be cursed.
Ring of item protection (ported from Rogue's ring of maintain armor): protects all inventory items from damage of any sort, which includes outright destruction such as monsters casting destroy armor and ring/wand explosions. Also includes protection from disenchanter disenchantment.
Wand of detect magic. Non-directional; if you are carrying any items in your inventory which are magical, "You feel a magical aura inside your knapsack.", and any object classes in open inventory which are magical but not type-identified are identified as being magical.
Nuggets of various metals (copper, gold, iron, silver, mithril, maybe generic metal). These are all * class and are basically rocks but worth more.
Stealing gloves. 0 base AC, and Rogues begin the game wearing a pair. When you hit a monster barehanded while wearing them, you deal no damage (and don't train bare handed combat skill) but you get a Dex-versus-monster-AC chance to steal a random non-equipped item or some gold out of their inventory. You can also attack a peaceful monster with them to attempt to steal something; in addition to the Dex-vs-AC roll, this requires passing both a Dex check and a Cha check for them not to notice. If the Dex check fails, you don't steal anything successfully; if the Cha check fails, they notice (waking up if asleep) and get mad. If the stolen item is currently equipped, there's no Cha check; the monster just gets alerted and angry.
Dowsing rod: chargeable magical tool that when applied tells you the total value of all gold and gems on the level that isn't being carried by the player (but not their locations), and whether there are any artifacts on the level that are not carried by the player.
Potion of honey; nonmagical but provides a lot more nutrition than juice.
Amulet versus theft, which negates the attacks of leprechauns and nymphs.
Ring of gold detection, which provides persistent passive gold detection in a radius. Lets you see how much gold a monster is carrying when you chat to them or use a stethoscope. Vault guards are guaranteed to carry one; leprechauns rarely generate with one.
Another type of magical horn that when improvised on creates allied monsters (dead heroes?)
Potion of elixir, which heals more HP than healing, but less than extra healing. It also recovers the same amount of Pw and restores 1 ability point in all attributes. HP and Pw maximums do not get raised.
Boots of earthquake: when you stomp the ground with them (by kicking downward), an earthquake happens. However, this spends 1 point of enchantment on the boots (not going below 0; if they are 0 or less then no earthquake happens.)
Gloves of fortune, which unlike SporkHack cause killed monsters to drop d10 gold pieces that didn't previously exist, and rarely a gem.
A magical whistle that instead of warping pets summons a temporary ally who disappears after a while.
Skeletons for vertebrate monsters. Corpses turn into these when they rot away. They cannot be undead turned into their monster; trying to do this will create a skeleton monster instead. Lawfuls might get an alignment boost for burying a skeleton in a pit and filling it.
Gold nuggets as a replacement for loadstones. They are expensive, but generate cursed. Like loadstones, cannot be dropped when cursed.

Object behavior

Breaking an amber stone (e.g. when fired from a sling and hitting a monster) has a chance to release a random a.
Applying a blessed whistle (either type) will unparalyze pets in range.
The amulet of restful sleep confers hungerless regeneration whenever the player is asleep.
Rename the two-handed sword to "greatsword", moving "two-handed sword" to its unidentified description.
When the hero #sits in a corner while wearing a dunce cap, give YAFM and exercise wisdom.
When breaking an identified wand of nothing, give YAFM: "Predictably, nothing happens."
Similar to object properties, a small fraction of wearable items are generated with a "trendy" attribute, which is not hidden from the player. Trendy items have an increased base price and add one charisma when worn.
Reading a blessed scroll of fire allows you to select a spot to center the blast of fire, similar to the selection for a scroll of stinking cloud or the advanced fireball spell. The damage of this scroll is also increased somewhat from what it is now, about four times the current damage, to make it worthwhile to use. (This has been added to vanilla 3.6.1 by paxed.)
Whenever a diluted potion of acid would be created (i.e. by wishing or polypiling) it immediately explodes in an alchemic blast.
Flip the blessed and cursed effects of the scroll of create monster, with the argument that if beatitude influences an object's effects at all, blessing should amplify them and cursing should reduce them. However, consistency along these lines conflicts somewhat with the current behavior of objects, which is that blessing generally always gives the player a better effect and cursing gives them a worse one. The create monster scroll is in a weird place because both its blessed and cursed effects could be considered beneficial in different contexts.
A blessed scroll of destroy armor should allow the player to select which piece of armor to destroy. If they decline to choose, it selects a random piece of armor like the uncursed scroll.
The Platinum Yendorian Express Card is made out of literal platinum instead of plastic.
Boomerangs should keep flying when they hit monsters, for the slapstick comedy value and also because it makes them a nicer weapon.
Colored glass frequency corresponds to its real-life frequency; red, orange, and yellow glass are rare; green and brown common, etc.
Junk mail is not only addressed to the finder of the Eye of Larn, but contains references to other games too.
Objects thrown at cloaked or hidden monsters pass right through the square as if no monster is on the square.
Because you pass beyond the mortal realm when you exit the Dungeons with the Amulet, life saving does not work in the End Game, at all, even for monsters.
You can apply a spear to hit things two spaces away like an unskilled polearm.
When a bag of holding explodes, each item inside has a 1/13 chance of being destroyed and a 12/13 chance of being scattered (using the same code that scatters drawbridge chains).
Reading a scroll of confuse monster while confused confuses nearby monsters in a large radius akin to confused taming.
Invoking the Staff of Aesculapius allows you to select a direction. If you pick a direction with an adjacent monster, the monster will get the healing effect instead of you. If you aim at yourself or a direction with no monster, the healing effect applies to you as normal.
The wand of speed, zapped at yourself, grants temporary very fast speed and does not grant intrinsic speed. Intrinsic speed can be gained from a non-cursed potion of speed, and a blessed potion will still grant temporary very fast speed. These would be more useful in a system where permanent very fast speed is unobtainable.
Writing an unknown spellbook is not as likely to fail outright as it is now. Instead, there is a chance that it will "warp strangely, then turn <color>", and become some other unknown spellbook.
Speed boots' speed is gently nerfed to be better than intrinsic speed, but worse than temporary sources.
Non-erodeproof copper items corrode over time.
Accuracy, damage, and AC bonuses should not be available as intrinsics, and eating their rings should not do anything.
The cursed Book of the Dead will occasionally raise the dead around its location on its own without warning.
All the various fruits and vegetables have slightly different (and generally good) non-nutritional effects, like with carrots and blindness. Ideas: Apples exercise Consitution (and make nurses flee?). Pears heal d3 hit points. Oranges restore one lost ability point. Bananas cure stunning.
Putting on a ring of protection from shape changers and causing a shapechanged monster somewhere on the level to revert to its normal form wakes it up if it's asleep.
A blessed scroll of light lights up the entire level.
Hitting monsters with a non-cursed unicorn horn cures them of status afflictions. Hitting them with a cursed horn gives them status afflictions.
The amulet of life saving should not work if you are nonliving.
The amulet of life saving does not restore the hundreds of hit points it can currently restore; it restores something on the order of 6d10, enough to quaff a potion of full healing, but not enough to repeatedly put on more amulets and let the massive HP store run down on its own.
Spellbooks cannot be written by appearance. If you don't know the spell, you can't unknown-ID write it based on appearance (though you can still try to make an attempt to write it based on the spell).
When tossing a corpse upward, it usually doesn't do any damage unless it's quite heavy.
Improvising on a wooden flute may compel all r monsters within its audible range to move closer to you or follow you, a reference to the Pied Piper of Hamelin.
When you zap a wand of undead turning at a corpse that has an undead form, unless there is a ghost above it, it will resurrect the corpse as that undead. Also do this for living monsters that have undead forms, subject to monster magic resistance.
Wearing a cheap plastic imitation of the Amulet of Yendor gives you the sucker markup in shops.
New container trap effect: a monster is generated from the box (was hiding in the box and pops out at you), taking you by surprise. It gets a free attack on you.
New non-magical gauntlet which is metal and has no special effects but has 2 or 3 base AC. Knights start with it instead of leather gloves.
Potions of acid have a splash radius effect when broken (could probably be implemented as an acid explosion).
In variants that have mud or muddy swamp terrain, wearing mud boots confers a benefit on that terrain (depends on what the terrain does).
If you try to drink a potion underwater, it will first dilute the potion. This means that an undiluted potion will become diluted (but will generally be fine to drink), a diluted potion will become water (and thus useless), and a potion of acid will blow up in your face.
Swap the blessed and cursed effects of the potion of acid, which means that blessed acid is more powerful acid, while cursed acid is kind of cruddy.
The "weakest" BUC of the potion of acid may not cure stoning.
Detect monsters shows invisible monsters as I (or whatever S_invisible happens to be).
Zapping a digging ray upward may either detach a boulder from the ceiling, or several rocks, instead of a single rock. If several rocks are released, each gets a separate damage roll.
Darts can be dipped in several different potions besides sickness to get different effects. Blindness, hallucination, sleeping, etc.
Recolor the lump of royal jelly to %.
The scroll of teleportation now levelports when blessed and teleports within a small radius when cursed. Confused teleport gives you a single controlled horizontal teleport.
If blessed, the potion of polymorph gives you control over your polymorphing form when quaffed.
Cans of grease are changed from iron to metal (or plastic), so they don't rust.
Unicorn horns are a one-handed weapon that does 1d3 damage, and train no skill (the skill is removed outright). However, when wielding one without gloves, you automatically "apply" it (not consuming any turns the same way as a stethoscope), every turn.
Wands of striking and digging tools deal double damage to all stonelike monsters (clay and stone golems, gargoyles, xorns, earth elementals etc).
Rubbing iron on a flint stone gives the message "Sparks fly from the stone".
Applying a looking glass cures blindness, in some very odd uncommon set of circumstances (like when hallucinating).
Getting hit in the head by a potion deals a small amount of damage (unless wearing a helmet). Death reason: "hit in the head by a potion"
Perfectly fine uncursed food should not make the hero pass out.
Corpses have significantly less nutrition than they currently do, and may be too mangled to be good for a sacrifice (this could be tied to its object ID). Their intrinsic-conveying chances are unchanged, though.
Amulets of change generate cursed no more than normal amulets (it no longer generates cursed 90.5% of the time).
Wielding and hitting enemies with a pyrolisk corpse deals fire damage.
Change the material of the oilskin sack to leather.
When dipping an oilskin sack in water, give a unique message "The water runs off the [bag/oilskin sack], leaving it dry.", which unambiguously identifies the oilskin sack. (This has been added to 3.6.1 by ais523.)
The scroll of genocide can only be targeted on monsters you can currently see. This means if you want to blessed-genocide L, you actually have to go and find a lich and read it in its presence.
Make somewhat more of the effects from dropping a ring into a sink not lose the ring.
The blessed potion of hallucination, in addition to making you hallucinate, grants enlightenment (maybe a "corrupted" enlightenment where there's only a 50% chance to see things you can't see through the ^X command)
Dunce caps are made out of paper.
Boulders deal 5d4 damage instead of 1d20.
Zapping the wand of opening (not the spell of knock) at a trapped door will cause it to blow up.
Confused cursed scroll of punishment decreases god anger by 1.
Wearing an oilskin cloak prevents theft attacks by nymphs, monkeys and leprechauns.
Breaking a wand of teleportation will teleport as many monsters around you as there are charges left in the wand, always including yourself.
Dropping a scroll of scare monster (or any scroll) on a fountain usually or always blanks it.
Spellbooks can generate pre-read. They will always have at least 1 use remaining in them (and that will be uncommon), but they are not always new spellbooks. If monsters cast player spells and generate with spellbooks to cast them (as in FIQHack), those spellbooks should be pre-read as well.
Flint stones should weigh 1, so they are not inferior ammunition to arrows and darts.
Buckled boots have a lower armor delay than other boots, since they are easier to attach to your feet.
Reflavor the hexagonal wand as being a quartz crystal and change its material to GEMSTONE.
Dipping a scroll of amnesia into some (or all?) non-polymorph, non-water potions will make the potion "forget itself" and turn to water. The scroll also blanks.
If your Intelligence is 6 or lower, reading a scroll may give its confused effect even when you are not confused.
Blessings or cursings on spellbooks does not translate to automatic success or failure. Instead, it acts as a fairly large bonus or penalty to your effective Intelligence when reading it.
You can read the label on tins. All player-made tins are unlabeled, while random tins will randomly (and deterministically) either say truly what sort of monster is in them, or have an irrelevant message. Messages could include: "Tuna Fish - expires Feb 6, 1989", "Rare Meat of a Genocided <hallucinatory monster>", "Water Chestnuts - be sure to eat while underwater", "Yendorian Brand Applesauce", "This Tin Is Not Booby-Trapped", "Fresh Tinned Adventurer Meat". (Implemented in xnethack.)
Confused genocide (uncursed or blessed) does not genocide you. Instead, it sets a level flag that prevents any more monsters from spawning on that level via the normal mechanism for the remainder of the game. (Monsters already created are unaffected.)
Make potions of oil undilutable.
When acid breaks on someone's head and spills on them, it actually does more damage than quaffing it, because it is spread out over more surface area.
For TDTTOE, wands of fire light potions of oil on the ground, and wands of cold snuff them.
Tins that don't contain monster meat can contain either spinach or spam.
Athames are a chargeable weapon-tool, or just a tool. Has tinning kit levels of charges and recharging. Once out of charges, it can't be used for a semi-permanent engraving anymore.
You need to have hands in order to operate a tinning kit or tin opener.
Amulets of change don't disintegrate when you put them on; instead they autocurse. Once you remove the curse and take off the amulet, your original gender is restored.
Scalpels can generate made of obsidian, which gives them extra damage due to a sharper edge, but they can shatter on hard monsters or armor.
The scroll of light gives the player a light radius of 3 for a temporary amount of time, rather than lighting up a fixed area.
Aligned priests generate with d2 or d3 potions of holy water, and priests of Moloch generate with the same amount of unholy water.
Buff the potion of gain energy so that it refills around 100 points of Pw. If this would take you above your normal Pw maximum, you get temporary Pw equal to that difference.
Remove the "unlabeled scroll" description. All roles recognize the scroll of blank paper for what it is.
There should be three ways to interact with potions: drinking them, getting them spilled on the exterior of your body (e.g. having them thrown at you and hit you), and inhaling their vapors. These should all be fully symmetric and have noticeable effects for most if not all potions.
Stinking clouds spread out from their origin point instead of using a preset diagonal shape. (Implemented in xnethack.)
The blessed potion of gain ability only gains one ability point, but it allows the player to choose which.
C-rations and K-rations are readable, which give the names of various real-life army food.
When you equip a ring of hunger or conflict, you get a message about feeling hungrier.
If you are wearing iron shoes, you cannot be hurtled to other spaces, unless you are levitating.
The confused scroll of magic mapping tells you where some special level or branch entrance exists on the main branch of the dungeon which you have not yet visited. If you have visited every special level including the Sanctum, it gives you a message about the DL 1 upstairs.
Dipping water into oil doesn't count as random alchemy.
Potions of acid and oil are immune to freezing and shattering.
Almost-rotten corpses, those that make "You feel sick", may cause you to vomit.
Chargeable ring (or amulet, if possible) of energy regeneration.
Dipping a spellbook in a potion of gain level turns it into a spellbook of some spell that is one level higher. You only get "Interesting..." if you try this on a level 7 book.
Convert the potions of monster and object detection into scrolls, since they are the only potions that don't really have an effect on the drinker.
Hungerful regeneration from the ring only costs excess nutrition if your HP is actually below full.
Silver objects are corrodeable but not, of course, rustable.
Shuriken may degrade in enchantment when they hit monsters, but they no longer break.
Add "gourmet" as a random tin preparation type, giving 350 nutrition. Also add "stale" as a tin preparation type, giving 100 nutrition.
Placing potions in an ice box makes them instantly freeze and shatter.
The non-cursed scroll of taming always pacifies monsters that can be pacified and are usually peaceful (shopkeepers, priests, watchmen). If blessed, this is extended to all monsters that can be pacified at all (nearly everything, except a few uniques). The MR roll to tame monsters is unaffected.
If you throw a wand < and hit yourself on the head with it, it consumes a charge and zaps yourself. Come to think of it, this should extend to wielding a wand and hitting monsters with it.
The default label for the scroll of flood is changed to EGULED EL IOM SERPA.
If you enchant multiple worm teeth into a single crysknife, the enchantment of the resulting knife is increased by 1 point for each additional tooth involved. This can go up to a maximum of +9, bypassing normal overenchantment dangers.
Meatballs, meat rings, meat sticks, and huge chunks of meat all become possibly tainted at the same age as corpses.
Restore ability (potion or spell) also cures wounded legs, "restoring your ability" to jump, kick, carry, etc, and will cure most status ailments as well.
Give a YAFM when you gain very fast speed from any source while hallucinating: "Gotta go fast!"
Polymorphing a corpse does not turn it into random food, but instead turns it into the corpse of a random level-appropriate monster. Discards any mextra information about the previously existing monster.
The ring of conflict autocurses when worn.
Trying to enchant multiple crysknives at once will fuse them together before trying the enchantment.
When a crysknife leaves your inventory, it starts a timer with 10-50 turns. The timer is canceled if it reenters your inventory. If the timer times out on an unfixed crysknife, it reverts to a worm tooth; if a fixed one times out, it loses one point of enchantment, or if it's at +0 it reverts to a worm tooth.
Amulets of change shuffle your stats the same as polymorphing into your own race (but no risk of a system shock).
Amulets of ESP occasionally randomly cause a detect unseen effect, because extra-sensory perception is more than just telepathy.
Failing to write an unknown scroll or spellbook just consumes an average amount of ink; otherwise it implies that the character knew how much ink the scroll would have taken.
The chance for writing an unknown scroll or spellbook is based not on luck but on how many scrolls and spellbooks you already have identified (and thus, how familiar you are with their sort of magic).
Eating garlic replicates the effects of the fountain effect "This water gives you bad breath!", causing all monsters on the level to flee for a limited time.
Wolfsbane has a similar effect to werecreatures when lying on the ground as garlic has on undead: they won't step on that space.
Greased scrolls and spellbooks, if they catch on fire, burn up and deal additional damage.
When you read a dusty spellbook, if you are currently in a breathing form, you may sneeze (same chance as a dull spellbook) and wake up nearby monsters.
Stethoscopes don't work on non-living monsters.
Whenever generating a corpse, check to see if it's during level creation. If it is during level creation, pre-age the corpse a la zombie and mummy corpses so that it's not weirdly fresh.
Cursed potions of gain level work in Sokoban, but they always place you on the > of the next level up instead of randomly, effectively letting you skip any level except the last one.
Remove restore ability vapors healing monsters to max HP, because that makes no sense.
If you are not fully healed by a potion of restore ability, it prints some other message than "You feel completely healed".
Increase the price of the magic whistle to 50 zorkmids. Identification of the whistle type is trivial anyway.
Some charged items (such as horns of plenty, crystal balls, and other charged tools) slowly recover charges over time on their own up to a reasonable maximum. Possibly, also make magic whistles a charged tool that recharges fairly fast.
The cursed scroll of remove curse removes the curse from one item in your inventory at random, to give it at least a tiny bit of use.
Allow ammunition to be treated with various potions, such as sleeping and confusion potions, to cause adverse effects on monsters. This can be done by overloading the corpsenm flag on ammunition.
Rarely, and only once per game, name a randomly generated large box "Pandora's Box" upon creation. Such a box contains a ton of good loot, but opening it (or destroying it, or tipping it) alters several overarching gameplay mechanics that all make the game tougher.
When you put on cursed gear or worn gear becomes cursed, it gives you a message that it welds to the appropriate body part. When becoming uncursed, it gives you a message that it is no longer welded.
Object materials: cursed gold items cannot be dropped.
Every lock in the game has a deterministic chance (based on object ID if a box and xyz coordinates if a door) of being unopenable by a credit card. Attempting gives the message "It doesn't look like this lock can be opened with a credit card."
- Boxes have a constant 40% chance of being like this, and doors are based on depth, starting at 10% or so on level 1 and increasing to 80% by level 50.
- Possibly extend this behavior to locks that can't be opened by a key either, requiring picking or magic.
Attempting to pick a lock with a credit card may result in it slipping through the crack (ending up either inside the box or on the other side of the door). The chance for this is getting a 1 on a rnd(Dex*2) roll (with an uncursed card; cursed cards will always slip through and blessed ones will never slip through). If fumbling, use Dex/4 instead of Dex*2.
Beams and rays from wands have a slightly reduced range if the wand is cursed, and a boosted range if it is blessed.
Homemade tins will give you their monster's base corpse nutrition if that is lower than 50. (If it was higher than 50, it'll still be reduced down to 50.)
Every unicorn horn cures one type of ailment and no others.
Make the ring of slow digestion's effects totally opposite those of the ring of hunger: rather than cancelling your normal digestion entirely, it only stops you hungering on every other turn, effectively increasing the hunger rate from 1/20 to 1/2.
Lances go through one or two levels of visible damage before being destroyed completely, rather than being able to break outright.
Reading a noncursed scroll of remove curse will also cure any lycanthropy you are suffering.
The amulet versus poison (and only this) prevents food poisoning from tainted corpses.
When you take shock damage, any brass lanterns you are carrying in open inventory get recharged an amount proportional to the damage taken (possibly up to only 1/3 or 1/2 of its maximum charge).
Hitting a statue with a wand of opening (possibly the knock spell too, but it might be nice to let the wand have a fringe benefit) causes it to drop all its contents without breaking.
Statues of a monster occasionally contain a figurine of that monster inside.
Dipping a unicorn horn into a potion of a type it normally "cures" will do nothing if the potion is cursed.
Enchanted boomerangs can continue flying after hitting a monster, with an enchantment/7 chance. (Add 2 to the effective enchantment if the boomerang is blessed; subtract 2 for each successive monster it hits.) If the boomerang is cursed, enchantment doesn't matter - it will always fall on the first hit.
Tinning kits are lighter, but generate with a small amount of charges rather than the large amount they currently have.
Revamp ring explosion on charging them: a ring enchanted to a positive value has a enchantment in 7 chance of "vibrating unexpectedly" or something similar. This is a warning and, like weapon vibration, does not hurt the ring. If you get this message, the ring's otrapped flag is set. Charging a ring with otrapped set always explodes it. There is no way to ascertain the otrapped value of a ring. Discharging the ring via cursed charging or drain life has a 50% chance of removing the otrapped flag per point lost.
Blessed potions of gain level give you at least 75% of the experience points required to reach the next level, instead of being totally random.
When a potion of oil gets hit by fire, it ignites and explodes.
Generalize cockatrice-egg mechanics to all eggs: eggs of acidic monsters will be acidic, eggs of poisonous monsters will be poisonous. Possibly even have a (reduced) chance of getting intrinsics from a monster egg.
A statue hit with opening magic will drop all of its contents without breaking the statue.
Applying a cursed bag of tricks sometimes causes it to explode, causing magical explosion damage to you while also expending all of its create monster charges at once.
Eating a carrot is "crunchy", and it may wake monsters around you due to being so loud.
Rolling a boulder on ice makes it slide for up to 10 squares (provided it keeps sliding over ice) before stopping. It is treated like a rolling boulder trap, capable of hitting monsters in its path. This mechanic could be used in Sokoban to create interesting puzzles.

Spells

New spells

Add lightning as level 5 attack spell, at Unskilled and Basic has the same effect as a wand of lightning, at Skilled and Expert explodes on its first target
Spell of repair: level 3 matter spell. If wielded weapon is eroded, fixes its erosion. Otherwise, target a random piece of worn armor and fix any erosion it has. At Unskilled, the erosion will only be repaired 1 level at a time; at Basic, 2 levels; at Skilled, 3 levels; and at Expert (maybe) the item will be erodeproofed.
Spell of shove: level 4 or 5 escape spell. At Unskilled and Basic, it fires a beam that pushes the first monster it hits back one space (as if receiving a staggering blow, but doing no damage); at Skilled and Expert, it fires a shorter-range beam in all eight directions. Seems like it could be pretty fun, what with shoving monsters into moats to drown them and things like that.
Ring spells, level 7 (or even 8) attack spells, which cast a ring of some elemental power emanating from your square that does not hit your square itself. The radius is 1 if Unskilled or Basic and 2 if Skilled or Expert.
Spell of baleful polymorph: a beefed-up version of polymorph (or an advanced form) that, when it polymorphs a monster, allows you to determine what to change it into. Perhaps this does not work on pets, so you can't give yourself a army of titans.
Level 1 divination spell "waypoint", which reveals the location of all stairs/ladders (but no other spaces) on the level. Does not work if the level is unmappable.
Add a spell of paralysis, which basically steals the same monster spell. Melee range, better than sleep. Or, alternatively, make the sleep spell better with higher skill.
Spell of earthquake, mid-level matter spell. Causes an earthquake centered on you; range and power varies based on your skill level.
A spell that provides see invisible (but the potion should be objectively better than it by at least an order of magnitude).
Spells that give temporary to-hit or damage buffs. Must be carefully balanced; this is intended for fighter classes more than wizards. It also can't last long enough or should be expensive enough to not have on all the time.
Animate monster spell: if you cast it at a pile of objects with the correct material, it creates a tame golem of that material.
Illusion / disguise self spell: Makes a monster appear as a different permonst of its choice. Perhaps if you have extrinsic see invisible, you can see through such illusions. Would be more effective in monster hands than player hands (perhaps in player hands they can disguise themselves so that monsters who didn't see them cast the disguise have a chance of being fooled and not attacking).
Summon single nasty: summons only one monster, but the game looks at the target's current gear and defenses and analyzes exactly what sort of monster would be the best for facing it.
Monster spell that either generally or specifically debuffs the player. It targets beneficial timing-out intrinsics you have, such as speed, detect monsters, and see invisible, and reduces their time remaining, possibly removing them outright. Does not affect permanent intrinsics or extrinsics.
Spell of create undead: turns a corpse you're standing on (or adjacent to you) into a tame undead, but only if an undead monster exists for that kind of corpse. Zombies at low levels, then mummies; eventually higher-level stuff like skeletons and maybe even vampires. Possibly creates wraiths or ghosts for other types of corpses of intelligent but no-undead-counterpart monsters. Can be used on corpses of slain undead.
Spells whose main purpose is to buff allies within an area of effect. (They will give the player the buff too, but since the buffs won't be a huge improvement for a single creature, you get more out of the effect the more allies you can affect with it, it's best used when you have allies around).
Spell of blindness (possibly also available as a wand), which blinds monsters.
Spell of necromancy that can animate corpses into tame undead. Probably in the clerical school, though a case could be made for matter. You can only create undead if it's a suitable monster (i.e. a jackal can't be turned into undead but a gnome can turn into a gnome zombie/mummy). A higher caster level lets you create more powerful undead. At a high enough level, you can create tame ghosts, wraiths, and even shades from the corpses of any intelligent monster. Casting this spell would have some sort of penalty for lawfuls; there would be some sort of warning before trying to cast it.

Changes to existing spells

Reduce level of turn undead to 2 or 3.
Reduce level of invisibility to 1 or 2.
Cure blindness is a pretty useless spell, and should probably be removed or its effects folded into some other spell like extra healing or clairvoyance. Alternatively, if see invisible is nerfed so that it cannot be granted permanently, this could be folded into a "spell of true sight", which grants temporary see invisible as well as curing blindness, perhaps temporary blindness resistance, and blocking (but not curing) hallucinations like Grayswandir's wield effect.
The spell of clairvoyance grants a few hundred turns of intrinsic clairvoyance when cast at Skilled. This makes it useful for Samurai in particular.
Spells now take different numbers of turns to cast (interruptable by normal means). Combat spells and some of the emergency spells still take only 1 or 2 turns, but utility spells can take up to five or so.
Nerf the spell of charm monster heavily. It never tames a hostile monster directly. If it would have succeeded, it only pacifies the monster. Peaceful monsters can be tamed on subsequent casts, but trying and failing to tame a peaceful intelligent monster may anger it. Pacifying a hostile monster is dependent on monster MR, while taming a peaceful monster is dependent on the relative levels of the player and the monster. The scroll of taming should be more powerful and reliable than the spell.
The spell of light has an advanced form, which is a ray. It blinds monsters it is fired at like a camera flash does. (The camera flash is also transformed into a ray, which can be reflected.) In Wands Balance Patch-implementing variants, the wand of light should also have this effect for skilled users.
The spell of protection does not gradually dissipate. It disappears all at once, with the player given a warning a few turns beforehand.
The base Pw cost for a spell is specified per-spell, and only correlates with spell level rather than being tied to it, which allows for interesting things like low-level spells that are easy to cast but expensive.
Rename cone of cold to "frost blast", because it does not act like a typical D&D cone spell in either of its forms.
Zapping an opening beam at an already unlocked but closed door opens it. Casting knock at Skilled or Expert lets you unlock and open all at once.
At high skill, the spell of wizard lock forces items off the doorway to adjacent squares so it can make the door. If there's a monster on the door, it becomes embedded in the door.
In variants with the Wands Balance Patch, or otherwise have multiple levels of lightning power (Skilled lightning spell or something), lightning should chain into other monsters near the first thing it hits. Chain lightning can still be reflected. The jumps are made in random directions, so hitting a monster close to you may cause it to chain back into you.
Move the spell of light to the clerical school.
Make the spell of detect monsters level 2 or 3.
Reduce haste self to level 2, but make its duration significantly shorter.
The spell of invisibility has an advanced form which casts a make invisible beam, like the wand does.
Trying to cast a forgotten spell and getting nightmarish images in your mind drains a few points of Pw.
Magic missile damage depends solely on skill and not XL. (Perhaps realized by scaling its damage die size - d4 for Unskilled, d6 for Basic, d8 for Skilled, d12 for Expert.)
The spell of remove curse may be cast offensively at monsters to bestow a curse.
Give Healers at least Basic skill cap in enchantment spells, maybe Skilled.
The healing spell is a ray. Monsters will cast it on their buddies, but they might also hit you. But now that it's a ray, it'll bounce off you if you have reflection.
Summon nasties can only summon nasties on squares adjacent to the target player. If the target is completely surrounded, it has no effect.
When you are hit by the aggravate monsters spell at melee range, you gain intrinsic aggravate monster for a little while.
Distinguish between monster spells "summon random monsters" and "summon nasties", allowing lower level casters to summon at-difficulty non-nasties.
The player can never learn, or can learn but never cast, spells that they are restricted in.
For role differentiation: each role can only learn up to a certain amount of spells. Wizards can learn them all, while roles like Healers can learn about a dozen; valkyries might be able to learn 3 and barbarians 1 (or 0). Possibly combine this with the above idea.
The player can cast destroy armor at other monsters at melee range.
Make the sleep spell scale like it does in D&D: you can only put a total of (your level) HD of monsters to sleep.
Detect unseen grants temporary intrinsic searching in addition to its usual effects.
Flavor the spell of protection's messages differently if you are a Priest.
Nerf the spell of knock in comparison to the wand of opening: it should be a melee-range spell (or a beam with range 1), and possibly it can't be used to open containers until you are at least Basic in matter spells.
Alternatively, remove the spell of knock entirely in favor of the wand already being a good enough source of opening magic.

Artifacts

New artifact dagger The Barrow-blade of Cardolan: has some flat bonuses, some additional bonuses versus undead, and instakills all W, ghosts, and shades. It is either lawful or unaligned. Could also be a short sword, since there are currently no artifact short swords, but for flavor it should be a dagger.
When the player kills a giant spider with an elven dagger and Sting has not yet been created, the dagger is converted into Sting automatically. Sting is made of rustproof steel, instead of wood (this would be tricky to do because of base items; you would still want to be able to create it by naming an elven dagger, but Sting in the lore is made of steel or at least metal, not wood). Sting has bonuses versus spiders, in addition to its bonuses against orcs.
Add a non-wielded-weapon non-quest artifact that is a guaranteed first sacrifice gift for Monks.
One such artifact is The Silver Star; an artifact silver shuriken that deals +d8 damage to all targets. Like Mjollnir, it returns to the player's inventory after being thrown, but doesn't have any chance of hitting the player. Since there is only one of it, it cannot be multishot.
Add one or two artifacts or modify artifact base types such that there is more than one good blunt artifact you can obtain through sacrifice. (The current three are Mjollnir, which is decent, and Ogresmasher and Trollsbane, which are not.)
Make Sunsword out of gold.
Nenya (Galadriel's ring from Lord of the Rings): a mithril ring that confers unchanging and warning across the whole level when worn.
Scrivener, an artifact magic marker. It generates with 3 charges and cannot be recharged. Instead of using the charges normally, a single charge will write any scroll or spellbook without fail.
Elfrist, a chaotic orcish dagger which can be named. It has bonuses against elves, of course, but also a smallish flat damage bonus versus any monster, so it might actually be useful to name it early.
As part of artifact weapon rebalance, there should be at least one Ranger-friendly non-bladed weapon that's available through sacrifice (and therefore available pre-Quest.) Doesn't necessarily have to be a bow.
Non-weapon artifact which, when carried, adds bonus fire damage to all of your physical attacks, regardless of source.
The Orb of Detection confers passive detect unseen: every few turns when carried it triggers the effect of zapping a wand of secret door detection for free.
Artifact instruments that are actually useful.
The Magic Mirror and Master Key's rumor-granting effects are removed or replaced, because they're stupid and a way to read the whole rumors file while still technically sticking to unspoiled behavior.
The Tsurugi always bisects long worms, cutting them in half.
Artifact whose carry effect deflects incoming status ailments onto nearby monsters. If there are no other monsters around (or if there is one monster who is causing the ailment and is ineligible), you take the status effect like normal.
Gungnir, an unaligned artifact spear (spear of Odin). Confers nothing, but has +20 to hit (or whatever is necessary to make a hit basically guaranteed) and +d8 damage.
Convert the Master Key of Thievery's base item type to a lockpick. Because flavor-wise, giving Rogues a key means they never have to pick locks again.
If an artifact has been generated, but is just sitting around unused on some level, wishing for it will remove it from that level and teleport it right into the player's hands. However, the beatitude, enchantment, and other fields of the wish will fail.
If Magicbane has not yet been generated when the player reaches Wiz-goal, Newt the wizard has a higher-than-usual chance of being given it.
Fire and Frost Brand can be invoked for powerful fire and cold bolts.
Sinsword, a chaotic artifact two-handed sword. If your alignment is positive, it behaves just like a regular two-handed sword. If negative, it gains a bonus to to-hit and damage (capped at 6) based on how negative your alignment is. Deals double damage to A.
Green Thumb, artifact (wooden if possible) gauntlets of dexterity, or gauntlets of defense if implemented. Invoke to create a tree. While you have them equipped and you are near a tree, you get some extra damage reduction.
The Orb of Detection confers automatic searching while carried, with a 100% chance of succeeding.
The Captain's Hook, artifact grappling hook that never fails to do what you want it to do and has zero chance of hooking yourself, regardless of skill. Deals double damage to crocodiles.
Make Demonbane a mace rather than a long sword, to make it more attractive to Priests.
The Silver Shoes, silver low boots that levelport you when invoked.
Artifact brass lantern that gives light in a radius of 4. Invoking it recharges it.
Fishing Pole, some sort of polearm that deals double damage to all sea monsters and can hit squares as if you were Expert, regardless of skill.
Demonbane, while wielded, warns of demons.
Make the Mitre of Holiness invoke effect give temporary intrinsic energy regeneration rather than a single huge boost of power.
Artifacts whose base item type isn't chargeable can be charged; this will clear or reduce any invoke timeout remaining.
Trollsbane can be invoked to instapetrify all trolls in a radius of 5.
The Mirror of Venus, a mirror that confers slotless reflection and charms monsters when invoked, but only if the character is female.
When an artifact is destroyed, unset it as existing so that it can be gifted or wished for again.
Intelligent non-quest artifacts will evade your grasp if you are directly cross-aligned (lawful when it is chaotic or vice versa). I.e. a lawful can never pick up Stormbringer and a chaotic can never pick up Excalibur, though neutrals can still can and will still get blasted.
Simplified Mirror Brand, based more on dNetHack's mirror blades than its own Mirror Brand. It is an artifact short sword that grants reflection when wielded and when it hits an opponent, takes the higher of its own base damage roll and the other weapon's (then adds its own enchantment to the result).
An artifact often gifted to Barbarians which provides magic resistance and half spell damage but prevents Pw from regenerating.

Level generation

Iron doors, which generate 30% of the time a normal door would be generated on dungeon levels 7 or below. They use the symbol +. They work the same as normal doors, but they cannot be burned, kicked, or blasted down, or destroyed any other way. If one happens to be locked, you have to unlock it "properly".
Any lava plain levels that generate should grow the region of normal floor by 1 in each direction, so that the player does not have to walk on narrow and diagonal paths through it. Ideally, this should be provided as a flag to any cavern-fill levels.
Place a statue of every demon lord who has not yet been generated lining the walls of Moloch's Sanctum. This way, if you really want to fight one (or all) of them, you can do so.
Scale the probability of secret doors and secret passages in a room-and-corridor level based on its depth, so that level 1 is almost guaranteed not to contain any blocking the way, and the other early levels are also not likely for this to happen.
Mud terrain, brown }. It can be walked on, but if you stand in one spot for long enough you will start sinking into the mud. You will be able to pull free if you are only a little stuck, but once you get more stuck you cannot, and if you cannot extricate yourself somehow you will eventually sink below the surface and suffocate.
Slightly increase the minimum depth of boulder traps, which is currently 2 and can instakill a character on level 2 easily.
Upper Mines levels' stairs are biased to generate relatively close to each other.
New "hedge" terrain #. It blocks movement, can be chopped down with an axe, has a chance to block ranged weapon attacks, and does not block line of sight.
Touchstones can generate in tool shops.
Containers never generate with food. Instead, split up the probability of food among other object classes that have nonzero probability, and also allow some tools to generate in them.
Instead of being completely lit or unlit, Mines levels can generate with large contiguous areas of lit and unlit floor.
Add a level attribute which serves as a multiplier for the monster spawn rate on that level. Can be specified in des files.
Open doors can generate trapped. When you step off an open door to some other space, it closes and locks behind you.
Sconces found on the walls of dark rooms, and in dark Mines levels, that may contain (lit or unlit) candles. You can #untrap or #loot them to remove the candle. Could also generate with a lamp, which would give you a potion of oil or a partially filled lamp when looted.
A very small percentage of closets have a random item generated in them, even if they aren't sealed off.
Track the number of unattended altars generated in the Dungeons of Doom above, say, the Quest portal level. If zero have been generated yet, the chance of one generating on a new level in that range increases more and more until it's a certainty on the final one.
The Mines have a higher mineralize rate for gold and gems than the other branches.
If fossils exist, they should generate buried under headstones.
Random piles of loot can sometimes generate buried in the floor or behind walls on spaces not adjoining any walkable spaces. Nearby engravings are generated to indicate that there is something in the vicinity. Archeologists get an alignment bonus for digging out these items.
Add a "specialness" value to each special room and possibly dungeon feature, based on their approximate usefulness to the player. (For example, a swamp room is virtually useless to the player, a treasure zoo not very useful, a throne room more useful, and a temple or shop the most useful.) A level will start out with some amount of specialness available, and randomly chooses special rooms and features to add until it runs out of specialness.
Trees' fruit is generated along with the tree (possibly buried for code purposes so that it shows up on object detection but not when you just look at the tree). When you kick or chop down the tree, this fruit is released rather than generating some fruit on the spot.
Put engravings outside or nearby inaccessible closets so that you know that something's there.
Some random graffiti is not rumors; it contains helpful in-game information. Things like "NR 9 is a scroll of earth" (giving object identifications), or "The Big Room is on level 12".
Aligned altars can generate in Gehennom, and standing on a coaligned altar in Gehennom is the only way to contact your god (via prayer or sacrifice). If the altar is crossaligned, you can try to convert it, but Moloch may seize control during the process and turn it into an altar to Moloch. Molochian altars are very difficult or outright impossible to convert.
Weapons and armor that generate in shops can be randomly eroded at any erosion level. Perhaps 10% or 20% of items are eroded, the rest are not.
Throne rooms generate their monsters awake, but also generate all their doorways as locked.
Sealed niches (with either a wall or iron bars) generate some additional item loot on top of their guaranteed scroll of teleportation.
When the game tries to generate a sink in a room, it tries to place the sink next to the wall.
Antholes contain eggs of the type of ant the room is filled with; fewer than the ants themselves.
Shops can sometimes generate disconnected from the rest of the level and must be teleported or dug into.
Assuming a new Gehennom generation algorithm which generates doors, some of which must be passed in order to get through the level: have a special type of "demon key" to open doors in Gehennom. Lots of them generate in Gehennom (though not as many as there are doors; possibly a certain type of monster there generates with them so you can obtain more if you get stuck), but each key is single-use and breaks when used to open a door.
Occasionally, instead of a werecreature corpse being placed in a closet behind iron bars, a live werecreature will be placed there instead.

New special rooms and shops

New shop type "thrift shop". Contains items priced at a steep discount but which aren't very useful on their own. Examples include negatively enchanted or eroded (not necessarily cursed) weapons and armor, blank scrolls, magical tools with zero or one charges left.
New special room "lich hall". Contains one difficulty-appropriate or somewhat-out-of-difficulty lich, generated asleep with difficulty-appropriate undead. One or two statues generate along the walls, and there are several spellbooks on the floor or in chests. Within the hall, the lich can summon more undead.
Storeroom: a special room that only generates in a dead end room. Contains 2-4 chests or large boxes, and rarely ice boxes. If the game had barrels, it should have some of those too. May contain a couple rats too.
One Gehennom "special room" should be an active temple with a peaceful priest of Moloch.
If cauldrons are added, new special room that contains several gnomish wizards, orc shamans, and kobold shamans standing around a cauldron.
Special "cell" room. Only valid if one end of the room has no doors. It generates a line of iron bars across this end of the room, with a locked (iron if possible) door somewhere in the line. Independently, it may contain: a prisoner, a sink, a bed (if those exist), and 1-2 chests with random contents.
Spider nest room; a zoo-fill with giant and cave spiders. Each square has a 70% chance of a web. Loot consists of several "bones piles" that have a few random objects but no comestibles.
New shop type "thief shop". Contains blindfolds, lockpicks, thiefstones (if implemented), rogue/pickpocket gloves (if implemented), cloaks and daggers. Something special should happen when you directly steal from a thief shop.
Gehennom special room "ice cavern", with mixed ice/regular floor, possibly with unnethack-style irregular ice walls, and containing ice devils and cold-themed items like wands of cold and rings of fire resistance.

Changes to special rooms and shops

If you are a Monk and the game decides to generate a delicatessen, replace it with a health food store 80% of the time. This is independent from the special case for health food stores in Minetown.
Vaults on deeper levels may generate with four gold golems instead of four gold piles. Or both.
Abandoned temples can generate as a special room, or else a room containing a random unattended altar may be converted into an abandoned temple.
Throne rooms should place the throne along one wall, preferably the narrower wall of the room.
Certain special rooms (typically ones that have awake monsters in them that shouldn't wander around the level) always generate with all of their doors locked.
Add code that allows the game to determine whether a room is a "dead-end" room (contains only 1 door which connects to the rest of the level, but unlike shop-compatible rooms, it's okay to have closets.)
Treasure zoos try to generate only M1_ANIMAL monsters.
Graveyards can rarely generate visible pits with no monster on top of them.
Monster lairs (antholes, cockatrice nests, etc) are not filled wall-to-wall with monsters.
Walled-off sections of graveyards with locked doors named "crypts" can generate. Inside crypts are very strong out-of-difficulty mummies. Note that this would require such strong undead to exist in the game in the first place.

Wishing for non-objects

Wishes are very powerful things, and I don't see any reason why they have to be limited to objects. I see this as a place to add interesting wishes with effects you can't get anywhere else.

Time: decreases the turn count a bit
Luck: increases Luck by d5 points
Intrinsics: gives you any intrinsic (that you can actually get in your normal form. Can't wish for intrinsic reflection, drain resistance, etc. Not sure about intrinsics normally only possible by eating jewelry.)
Attributes: increases whichever attribute. Maybe a d4 or d5 increase so it's not inferior to a blessed potion of gain ability.
World peace or just Peace: pacifies all monsters on the level, subject to normal resistances
Polymorph: you polymorph
Friends: same effect as a successful cast of create familiar
Terrain features: already wishable in wizard mode, the justification is "If the player wants to wish for lava, why not let them have lava?" You can wish for a throne, because the chance of getting two or more wishes off it is tiny.
Health: restores between 50% (or 75%) and 100% of your missing hit points, and cures all status ailments.
Elbereth: some TDTTOE message
A shop type: the next shop that generates will be that type
Happiness: gives you a blessed potion of booze

Conducts

Artifactless conduct: increment whenever an artifact enters the player's inventory (since the player never has to pick up an artifact).
Petless conduct: increment when the player starts with a pet or tames a monster. Can be accidentally broken by the taming effect of a magic trap; this bothers me. One solution is to have magic traps not tame if the player's pettype is 0, but I don't like that mixing of options and gameplay. In any case, polyselfless is another example of a conduct that can be broken accidentally and is far more likely.
Tins of "pureed monster" or "soup made from monster" do not break foodless conduct. Possibly change tin behavior so the preparation method can be discerned before eating it, or just display the preparation when the tin is opened, e.g. "You succeed in opening the tin. It contains a puree that smells like newts. Eat it?" This doesn't have to reveal every preparation method, so that greasy fried food remains a danger.
Polymonsterless conduct: you never intentionally polymorph a monster.

Religion and alignment

Divine lightning (a god smiting you, particularly Moloch when you attack his high priest) should ignore reflection; it's a "wide-angle" blast of lightning. Maybe this should apply to the clerical spell too, I'm not sure. The high priest of Moloch should also be shock resistant.
The protection penalty from failing to wear a helm of opposite alignment in the quest branch only applies if you know that it is a helm of opposite alignment.
Crowning makes it impossible to change alignment ever again. You can neither permanently convert at an altar or put on a helm of opposite alignment after you have been crowned.
Permanent alignment conversion prevents you from buying any more protection ever again.
Don't gift a character a spellbook as a prayer effect if the character is illiterate or certain roles (like cavemen), and if a spellbook is given limit its level somehow so that a character doesn't get a spellbook of much too high level.
One of the prayer boons you can get from a god is intrinsic light: you become a light source (probably of radius 3, but could be 4). Crowning may give you this permanently, since you're now all holy.
You get an alignment penalty for digging up a grave if you are a Priest.
When you kill the high priest of Moloch, Moloch himself shows up with the Amulet, and you have to beat him up and take it from him.
One possible prayer boon is that if you have more than a certain total level/total difficulty of monsters around you relative to your own level, your god will teleport you horizontally somewhere else on the level far from any monsters. If a non-teleport level, they will lift you up one level as a potion of gain level would; if that cannot be done, they will not choose this boon.
Replace all the priests of Moloch on the Astral Plane with priests of the other gods. Moloch is a disgraced, hated god, and his priests have no business there.
If you get hit by something reflectable, have no other source of reflection, and prayer timeout is 0, your god may rarely intervene ("But it reflects somehow!"). This could either increase timeout a smallish amount or not increase it. Does not break atheist conduct.
Your god considers both your luck and your alignment record when deciding whether to grant a prayer, and weighs alignment record more heavily. That is, if you have negative luck but good alignment, your god will often still grant the prayer, and positive luck might save you from bad alignment, but not often.
If a priest gives you two bits for an ale while hallucinating, change the message to "two bitcoins for an ale" (or just use a hallucinatory currency.)
The Arch Priest specifically offers to open up a magic portal to the Plane of Earth if you talk to him with the Amulet of Yendor, as a Priest benefit, to skip the last dozen or so levels of the Dungeons of Doom.
Worshipers of The Lady (neutral Tourists or some neutral Priests) have a permanent full-moon effect with Luck timing out to +1 due to the Lady's influence.
If a god doesn't have any good artifacts or spellbooks to grant you as a sacrifice gift, they give you a prayer boon instead.
A YAFM when you donate exactly 1/10 of your gold to a priest: "You pay your tithe."
Shamans count as clerical spellcasters and follow a god. If they follow your god, they are peaceful. Killing them will anger their god.
Add clerical spellcasters that are more dangerous than shamans but less threatening than priests.
When you are crowned, your character gains a literal ethereal crown above their head that causes monsters of (significantly) lower level than you to have to pass a resistance check upon seeing you or else flee.
Possibly, your god will not crown you until you have completed some milestone (finished the quest, probably, but also could be going to Gehennom and back).
Increase the rate at which annoyed gods will send down minions to defend their altars from being converted. (But only if you fail to convert it and the power of your god decreases.)
Magical taming is easier to do on coaligned monsters and harder on crossaligned monsters.
Rangers get an alignment bonus for disarming naturally-generated bear traps, or possibly for catching a hostile monster in a player-set bear trap.
"Awe" intrinsic, granted only as a divine boon for a short duration: any monster you hit or that attacks you automatically gets scared.
If the combined difficulty of nearby or adjacent monsters exceeds some amount, when you pray, your god may "fix" this by teleporting you to a safe location (preferring the upstairs whenever feasible).
Alignment penalty for Monks and Priests for consorting with a foocubus.
Monks' vegetarian-breaking alignment penalty is assessed at -1 alignment per X weight units of meat you consume. Eating a huge chunk of meat will cause a much larger penalty than a jackal corpse.
When you escape the dungeon by leaving on the level 1 stairs without the Amulet, your god is immediately set to be angry at you (for abandoning their mission). This will have no effect on the game since it's ending, but end-of-game enlightenment will show that they were angry with you. Possibly disable this if the hero had the Amulet at some point or is carrying an unidentified fake one.
Priests can sell holy water as a donation benefit.
Gods can grant you (unique?) pets as a sacrifice gift. Example here was Sleipnir for valkyries.
Praying while standing on a throne, assuming you're in good standing with your god, causes the god to have an increased chance of crowning you.
Fuzz the effective difficulty of monsters sacrificed, so that you can't trivially count up and calculate how much more you need to sacrifice.
The more gold you pay to a priest, the stronger his pantheon becomes. Newly generated priests from that pantheon could get better equipment, or altars of that god might be harder to convert. In Moloch's case, Gehennom gets slightly harder if you pour a lot of gold into his temple. This applies to your own pantheon as well, but the effects are not as visible.

Traps

New container trap effect, a loud alarm that wakes nearby monsters. (Exploding chests already wake nearby monsters, but the chance of it happening is miniscule unless your Luck is below -7; this was proposed as one of the common effects even at high Luck.)
Also a floor trap that does the same thing, sounds a loud alarm.
Rolling boulder trap hit chance and damage is based on dexterity and not AC, for how much you can jump out of the way. Only high dexterity will allow you to dodge the boulder entirely.
Using the m command to move yourself into a pit makes you lower yourself into the pit without taking any damage (so you can easily get items and other things in the pit). Maybe a spiked pit still deals a bit of damage, maybe not.
Rename rust traps to "water traps", and the gush of water hitting you may hit your pack, wetting several items.
Beartraps are now much lighter, and Rangers start out with two or three of them.
Polymorph traps have some percentage chance to disappear whenever they polymorph something. This is better for symmetry and means players might be able to deliberately polymorph themselves multiple times, but probably can't abuse it on behalf of their pet.
Dart traps can make you fall asleep, go blind, hallucinate, get confused, etc.
Egg trap, which shoots an egg at you. If it hits you, you get egg all over your face and your Charisma is decreased until you can #wipe the egg off.
You can #untrap falling rock traps. Unlike dart and arrow traps, this just dumps all the remaining rocks onto that space all at once. If there is a monster on this space, it gets hit repeatedly by each rock.
Falling rock traps never generate on levels that are open to the sky.
Rolling boulder traps don't expect a boulder at a specific spot: they look up to 9 squares in all 8 directions for boulders, and the first boulder it finds will be triggered. If no boulder is in range, it may create one by dropping it from the ceiling.
When a monster triggers a magic (or maybe polymorph) trap, one possible effect is that they turn into a figurine of themselves with appropriate beatitude. However, the trap exploding on them is more likely, so that it can't be used to farm figurines. A possibly evil addendum is that if the player would have otherwise died from damage from a magic trap, the bones file may contain a figurine of them instead of a corpse.
When you try to move onto a known trap with the m command, the game interprets it as you specifically trying to avoid the trap you already know about, and your chance of triggering it is greatly lowered.
Remove the odd feeling messages from magic traps. Instead move them to a new trap, a "foresight trap", which gives you a vision of something to come. Once triggered, the trap vanishes. Effects can be:
- "You hear a far-off song: .A.EF" - give part or all of the passtune
- "You have a vision of <something>" - reveal something about the dungeon structure, like "stronghold far below"
- "A shiver runs down your spine!" - create a level-appropriate "scary" monster somewhere on the level, like a ghost or other undead
- "You smell charred flesh." - create a level-appropriate monster with a fire attack somewhere on the level
- "You hear distant howling." - create a level-appropriate werefoo on a level above or below
The player can't cast spells or use magic items while standing on top of an anti-magic field.
Traps that shoot out potions. Generate with a variety of negative potions such as sleep, acid, lit oil, hallucination. Would work best if the trap struct contained a struct obj* pointer for ammunition.
Lighting a web on fire will burn it away, and also spread to any adjacent webs and burn through them.
When the player or any monster frees itself from a beartrap, it removes the trap and puts a beartrap item there instead.
The rumbling from a rolling boulder trap wakes up monsters.
Holes always drop you exactly one level (though trapdoors may still go farther).
Empty boxes are never trapped.
Occasionally when a pit or hole is generated, generate a random cloak on top of it (it's poorly covering the opening and the hero doesn't notice until they either search while next to it or step onto it).
If there are items on a pit space, the vision code doesn't render them until you're adjacent to the pit, at which point the pit is automatically mapped and you see the items. If there are no items in the pit, it remains undetected.
Monsters, including the player, under a certain body weight plus inventory weight don't trigger squeaky boards. This weight factor is fairly light, possibly in the low hundreds (so even a player carrying nothing will still trigger it).
Rangers have a significantly better chance than other roles at untrapping beartraps (perhaps even just 100%).
If there is a web over water or lava and you are a web-walking monster, you can move onto that space without falling into the liquid. Possibly if you're any monster, not just a web walker.
Container trap that teleports the container randomly.
When a magic trap shakes your pack violently, any bells you happen to be carrying get rung. For normal bells this doesn't do much besides awaken monsters, but the charged Bell of Opening will be rung, do its usual ring effects, and lose a charge.
Magic portals are never hidden.
If a monster steps on a squeaky board near you when you are asleep, it may wake you up.

Levels

A Mines' End that has a water theme, though not necessarily as extreme as the Gnomish Sewer.
The top level of Vlad's Tower is now an open level with Vlad and his throne, and the vampires and their chests are moved to lower floors.
Add a guardhouse to the Castle outside the immediate drawbridge area containing some soldiers and sergeants, where the player might find a bugle.
Add small jails to most if not all Minetown maps.
The Chromatic Dragon's lair contains several dragon eggs of random colors beneath the Chromatic Dragon.
Ludios uses a smaller, elite team made up of mostly captains and lieutenants for defense, with maybe some recruited dangerous monsters, instead of a swarm of soldiers.
Remove the Fake Wizard's Tower special levels. Instead, there is simply a doorway you can walk into on the bottom floor of the normal Wizard's Tower. (If it's desirable to keep the fake towers, let them be randomly generated features in Gehennom.)
Redesign the Wizard's Tower so the hero enters in the southeast corner on the bottom floor, spirals into the center with the upstair, the second floor has the downstair in the center and spirals out to the upstair in the northwest. The top floor has its downstair in the northwest and basically the same layout as now.
Remove the beehive from the Wizard's Tower. Bees are too easy for a late game player. If, instead, it should be kept (maybe a Wicked Witch of the West reference?), the beehive should open into the central area of that floor, so the bees can come out and attack the player.
Slightly bias priests' and angels' allegiances on Astral to be generated near their high altar so that the player can get a clue, but not enough so that it's obviously distinguishable from random noise.
Sokoban is a one-level branch that strings together a bunch of different puzzles that must each be defeated in turn, all eventually leading to the treasure zoo. Obviously, the pits must be changed to holes that drop you on the level with the Sokoban stairs.
Guarantee the Big Room in all games, and possibly expand the range of levels in which it can generate.
Orcish Town should bear more gear of the deceased shopkeepers and priests: there should be at least one key per dead shopkeeper, five dead shopkeepers' worth of gold pieces (probably to be picked up by orcs), a robe and spellbooks for the priest, and so on. Possibly even add gear for the wrecked shops. Or it should have a random piece of good gear being carried by an orc-captain.
The Astral Plane should be brightly lit, what with having all the halls of the gods and being suffused with holy power.
Mines' End variant that is an actual mine, with many twisty corridors dug out of the rock, and many unmined gems in the rock. The luckstone is unmined, in one of several possible spaces, not adjacent to any corridors but not too far away from them, and certainly not as far away as in the Wine Cellar. A pickaxe will be guaranteed somewhere on this level.
One of the Oracle's fountains is guaranteed to be magical, but it's randomly placed among the four fountains.
Vaults with undiggable walls. You must teleport into them. (The guard will appear inside the vault and teleport you out once you drop your gold.)
Gehennom level that is cavernous but with 1-3 defensive fortifications consisting of a slightly twisty undiggable wall with turrets or guardhouses staffed with demons, and lava moats with drawbridges. Stairs on opposite sides of the fortifications.
The Valkyrie quest home level should not be all ice. It seems like a frozen lake currently.
Many bear traps generate on the Ranger quest.
Guarantee a sack somewhere in Minetown.
A peaceful large dog named Sirius is found in the Ranger quest home level near Orion. Ranger starting dogs don't have to be named Sirius anymore.
The vibrating square level is just one big open rectangle with the vibrating square in its usual spots.
The spawn rate of natural monsters on Astral (and perhaps the other Planes) is zero.
Remove the guaranteed L and V monsters from Astral; the priests shouldn't tolerate random high level undead hanging around.
Add some Hitchhiker's Guide easter eggs on dungeon level 42.
Make the Vibrating Square level into, rather than just another maze level, a level with 3 symmetric 7x5 chambers embedded in the maze, each with four exits, and a smaller 3x3 chamber at the bottom containing the upstairs. In the center of one of the 7x5 rooms is the Vibrating Square. This is intended to be a dark mirror of the Astral Plane.
Add a clear and obvious ice theme to Asmodeus' Lair, as an indication to the player that he has nasty cold magic at his disposal.
A (maybe quest, maybe Rogue-locate) level that contains a pond outside some building or city wall, with one iron bars square on the other side of the wall, inaccessible except by going over the water. Behind it is a (maybe randomly generated?) network of corridors inside solid rock representing a sewer. Either there's something in here required to complete the level, or there's some treasure.
After the Valley, have a guaranteed special level "The Gates of Hell". This level design is very clear: "This is hell. These are the gates, and they are closed. You are not wanted here. Go away or perish." The level is a large cavern, with a massive arc-like fortification across either the left or right side. The gates are implemented with both iron doors and a drawbridge across lava. There is quite a lot of lava, and a lot of demons inside and outside the fortification.
Make the Wizard's Tower its own level rather than embedding it in Gehennom.
New Medusa-alternative level (like the Grue and Echo levels in dNetHack): Chrysaor's Palace, containing a fair amount of water, soldiers, and Chrysaor, who wields a +10 gold broadsword and a gold shield of reflection, and whose attacks and resistances are on par with Croesus or even better.
Redesign the Plane of Water: instead of moving bubbles, there is just a lot of water and little land; the water constantly sloshes around, changing the land and forcing the hero to follow it, but not every turn like the bubbles.
In the Big Room variant that has squares of light and darkness, make the lit regions circular rather than square (possibly just by scattering light sources).
Big Room variant that has a river cutting the level in half horizontally, with a bridge across it in the center. The upstairs is placed somewhere on the left; the downstairs and all the monsters generated with the level are placed on the right.
On the level containing the stairs to the Gnomish Mines, either always or often generate one gnome in a random place.
Make Fort Ludios a multi-leveled branch leading upwards; the upper floors are smaller levels with the same footprint as the base of the building on the bottom level.
Put some or all of Gehennom behind a one-way gate that you can't return past, by any means, until you have the Amulet.
Change Fort Ludios's door to a drawbridge, and add several more drawbridges leading into the throne room from all sides. When one drawbridge is opened or destroyed, all the others automatically open to let the monsters swarm out and attack.
A level or branch that forces permanent hallucination while you're in it. Hallucination blocking from Grayswandir may or may not function.
Level flag that prevents mapping as long as the local "boss" is alive (nemesis if anywhere in the Quest, demon lords/Croesus on their own levels). Maybe make the 'nommap' field 2 bits instead of 1.
Ranged divination effects (monster detection, object detection, clairvoyance, maybe telepathy) are suppressed if the level is not mappable.
Zapping wands of fire at the water on the Plane of Water boils the water away and opens up air space, but spawns in steam vortices.
Replace the Plane of Water bubbles with an initial map looking much the same with bubbles of air surrounded by water. However, instead of the bubbles moving on paths, run a fairly slow cellular automaton that shifts the water around gradually and will eventually join up the air spaces. It's possible for a bubble to collapse completely, but not if the player's in it.
Sokoban levels with water or lava instead of holes (and make it so that boulders never sink without a trace in Sokoban). Air currents will still pull you down into the liquid if you try to go over them.
Line the long empty corridor in Asmodeus' Lair with a few statues.
A Minetown containing a jewelry store, or add a jewelry store to Bazaar Town or one of the less plentiful Minetowns.
A special level where the region defined as the landing area for levelportation does not contain any stairs.

Bones levels

Bones levels have a special level sound.
Make bones a composite option that enables you to load only your own bones files, and never other people's.
When the player is killed by a carnivorous (or, more rarely, an omnivorous) monster, the bones file may not contain a corpse because it was eaten by the monster. Never happens if it would be cannibalism for the monster to eat you.
Occasionally, when a bones file would create a ghost (e.g. most times), and below a certain level, create a wraith of the player instead. If in Gehennom, occasionally create a shade of the player.
Bones levels should be saved as the deepest level the player reached in their game / the deepest filler level of its branch, unless it is a special level in which case it saves normally.

The Armory (Mines' End)

Map geometry is right center, and the left portion containing the upstairs will be normal caverns. The main monsters here are hostile (renegade?) G and h, with some "extra help" in the form of mercenary soldiers. The loot is in the form of armor and weapons in storerooms, with the gems and possibly luckstone in storerooms rather than scattered around. A random wand of opening is placed somewhere in the left side of the level, so the player can open the drawbridge.

----------------------------------------
|(.+..+^^|.+..}...|^^|..#..+...|.`.`...|
|..----^^+.|.h}.@.+^^+G.#..|.G.+G.G.G_.|
#G....|-+-.|..}...|^^|G.#..|...|.`.`...|
###GGG|.GG.-------|^^|G.#..|.G---------|
..###G|-----h.....|^^|..#..|..|***|[[[[|
....##|[.....----+---|.--++--.|***+[[[[|
..^...---+---|.......|+-....-+|*h*|[[[[|
........#GG#}|.#...#.+........|***|[[[[|
..###..^####}|...G...|########|-------+|
..#C#.......}#..GGG..|*hhhGG..+........|
..###..^####}|...G...|########|........|
........#GG#}|.#...#.+.......)|..barr..|
..^...---+---|.......|..|.|.-+|........|
....##|...+.(|---+-----.|.|.|.+........|
..###G|.---+-|....|...+.|.|.|.|-------+|
###GGG|.|....|.h..+.@.|.|.|.|.|***|))))|
#G....|.|barr|-+--|...|.|.|.|.|*h*|))))|
|..----.|....|^^|!--+--+-+-+-.|***+))))|
|(.+....+....+^^|}}}}|.......h|***|))))|
----------------------------------------

The dark + are secret doors. The four groups of red + are secret doors, but only one per group will actually be a door. All ^ are random traps. The * marked in magenta are possible locations for the luckstone. The brown ( are chests with the usual contents, and the marked ) is a blessed +2 two-handed sword. The two green @ are lieutenants.

All monsters behind iron bars get a ready supply of bows, crossbows, and ammunition.

Nonweapons in the wield slot

Wielding a mirror conveys partial reflection: you will reflect things 40 or 50% of the time.
Wielding a copper object protects against an otherwise successful disease attack some of the time, because copper is antibacterial.
When you wield a treat in your hand, pets that normally like that treat will follow you even more closely than they would if you simply had it in open inventory.
Wielding a wand will give you an accuracy or damage bonus with that wand. Or if the Wands Balance Patch is implemented, you get the effects of the wand at the next skill level. The nice thing is that monsters will always wield wands they intend to use, so you will usually see them doing so before they get a chance to take you by surprise with a fire or death ray.

Talismans

Talismans are slotless amulet-class objects that can be "activated" for their effect, which expires after 4000 + 64d50 turns. Once a talisman runs out, it either turns into a non-magical talisman (which cannot be restored to its magical state) or disintegrates, I'm not sure which. Once activated, they cannot be switched off to conserve their lifetime. They can, however, be charged to extend their life by a few hundred turns while activated. There is no limit to the number of talismans a player can have active at once.

Talisman types
Extrinsic	Randomized appearance	Color of glow	Auto-identifies	Material
Magic resistance	woven	gold		Cloth
Flying	feathered	blue	Yes	cloth
Hungerless HP regeneration	beaded	green		cloth
Power regeneration	patterned	green		wood
Astral vision	painted	white		wood
Drain resistance	weathered	gold		wood
Luck	furred	silver		leather
Warding (full magic cancellation)	aged	gold		wood
Clairvoyance	segmented	white		wood
Light (radius 5)	chiseled	white	Yes	wood
	carved			wood
	cracked			wood
	stone			stone
	leather			leather
	gnarled			wood

Something would probably have to be done so an ascension-ready player can't fire up a bunch of talismans at once before entering the Planes or Moloch's Sanctum. Perhaps there is a steadily increasing chance, dependent on the number of active talismans in inventory, that a talisman will disintegrate when a new one is activated or a previously activated one enters inventory. Any active talisman might disintegrate, not necessarily the new one. Having two active at a time is safe, but anything more is not.

The <talisman> sparkles and starts glowing <color>.: A talisman was activated.
The <color> glow of the <talisman> seems weaker.: A talisman is 100 turns from expiring.
The <color> glow of the <talisman> is getting faint.: A talisman is 10 turns from expiring.
The <talisman>'s glow disappears and it disintegrates.: A talisman expired.
The <talisman> shines with a brilliant light!: A talisman of light was activated.
You feel like flying!: A talisman of flying was activated.
The <talisman> glows violently red for a moment, then disintegrates.: Too many activated talismans were in inventory at once, and it disintegrated.

Staves

New set of short staff weapons. They either use a new "short staff" skill or just Quarterstaff skill (which would be renamed to Staff skill). They are inferior to quarterstaves as a melee weapon (a quarterstaff is a long heavy staff intended for pummeling; this is about half as long and held in one hand), doing d2 damage versus small and d1 damage versus large monsters, but they weigh only 10. There is one mundane staff that has no special abilities; the others are magical staffs that enhance a certain spell school when wielded by reducing spellcasting penalties and power and hunger costs for that school's spells. The Staff of Aesculapius' base item is now a staff of healing instead of a quarterstaff. Wood golems may drop these staffs in addition to quarterstaffs. Wizards will start with a staff of attack instead of a quarterstaff, or possibly a walking stick, depending on whether the Wizard early game is survivable with a plain walking stick.

While a staff is unidentified, it will not affect spell failure rates, so it is not trivial to identify. When you first successfully cast a spell of the staff's school while wielding it, you get the message "The staff attunes itself to your <school> magic", and the staff becomes identified.

Staff	Randomized appearance
staff of attack	yew staff
staff of healing	holly staff
staff of matter	ebony staff
staff of enchantment	hemlock staff
staff of cleric	redwood staff
staff of divination	oaken staff
staff of escape	maple staff
walking stick	pine staff

Magical gems

A set of gems that are very rare compared to other gems, and have magical properties. Their colors are randomized from all the available colors, and a blessed touchstone will mark them only as "magical <color> stone" without identifying what sort of magic it has. An uncursed touchstone will show colored streaks, the same as other valuable gems. All of these gems can be use-IDed, but the only other way to figure out what it is is formal identification. Polypiling rocks or gems will never generate a magical gem, and magical gems will always become mundane rocks or gems when polypiled.

Some gems are reusable, with charges, and can be applied or #rubbed for the effect. When they hit an enemy, they consume a charge and apply the effect to that creature or at that location. Others disintegrate on use.

Reusable gems

Teleport stone: makes the affected creature teleport
Sleep stone: makes the affected creature fall asleep
Shocking stone: deals fairly large shock damage to the affected creature
Earthquake stone: causes an earthquake at the affected location
Healing stone: heals the affected creature the same as if it had been hit by a spell of healing
Confusion stone: confuses the affected creature
Poison stone: poisons the affected creature, causing poison damage (and strength loss, if the player is affected)

Single-use gems

Branchport stone: branchports the affected creature (monster branchport can probably just be levelport)
Wishing stone: gives you a wish. These have an extremely low probability.

User interface or other technical things

The xlogfile shows which turn a conduct was first broken on, rather than compacting all conducts into a bitmask
Option to bring up the prompt to type-name an item any time it would normally be prompted, even if the object is already type-named. The example given is that if you price-id an object and then later see a monster use it, you then have the option to add this new information immediately.
The scroll of remove curse auto-identifies if it removes a visible curse from one or more objects (i.e. the player can compare his inventory before and after reading it and see that the curse is gone).
When the player is prompted to rename an object or a level that already has a name and submits an empty string, ask the player for confirmation to remove that name entirely: "Remove old name? [yn] (n)"
When farlooking and moving the cursor around, you can press "m" repeatedly to move the cursor to visible monsters on the screen in increasing order of distance from the player.
When standing on a (not known untrapped) container and pressing s, prompt the player to check for traps on the container. Search normally if they say no.
Anything the player touches is added to the discoveries list with a blank "called" string.
Engraving naturally interrupts instead of leaving the player helpless until it's finished.
For variants with object properties, store a bitfield as the property mask in the objclass struct, and a separate one in the obj struct. This lets you define which properties are inherent to the object type (e.g. acid resistance and poison resistance for an alchemy smock) and which abnormal properties it has, which is useful because all alchemy smocks shouldn't show up as "alchemy smock of poison resistance and acid resistance".
When blind and holding a leash with a pet on it, you can see the pet.
There should be a message from when you pacify (not tame) a monster by throwing food at it.
Fix the effective level difficulty of all Sokoban levels to either the level past the one with the stairs, or the level with the stairs, or 9.
You can displace peaceful monsters (but not shopkeepers, priests, or Quest leaders) by either walking into them (as the default choice) or by walking into them preceded by the m key.
Add a message for when create monster/create familiar/summon nasties fails to summon anything (may happen in extinctionist games).
The "You hear someone cursing shoplifters" message replaces "someone" with the name of a known alive shopkeeper on the level. (This has been implemented in FIQhack.)
In wizard mode, attempting to teleport into inaccessible terrain or into or out of a teleport region should prompt the player to confirm the teleport. If they confirm, they override any restrictions; if not, it prints "Sorry..." and works like normal.
Add a message for when an enemy demon gates in another demon.
The directional #loot command works on adjacent containers, not only on your own square.
Since untrapping is more common than the rarely used "seetrap" command, remap the ^ key to perform an #untrap. If you wish to use seetrap, you need to do #seetrap.
Opening your current space ("o.") should be equivalent to doing a #loot on your current space.
Split up the job of TELEPORT_REGIONs in .des files into it and NOENTRY_REGION. Now, TELEPORT_REGION defines a region that cannot be horizontally teleported into or out of, whereas NOENTRY_REGION defines a region where you cannot enter the level if arriving in an unusual way (level teleport, falling in from above, cursed potion of gain level).
Negative messages are never punctuated with ! and favor ... but may still use just a period. (Example: "You feel attractive..." for gaining intrinsic aggravate monster in FIQhack, the existing "You feel attractive!" sounds like you gained Charisma.
When a monster gets teleported away, show a message "The foo disappears!"
Allow the player to view the time as seen by the game.
Whenever a monster tries to read a scroll of teleportation and level teleports to the current level ("foo shudders for a moment"), you are prompted to call the scroll.
Add a level flag for the level being open to the sky or otherwise no ceiling. Effects of this include: falling rock traps do not generate, cursed potions of gain level do not work, scrolls of earth do not work. Levels that would have this: lots of Quest levels, the Elemental Planes.
The #terrain command shows unexplored spaces as ? marks.
The hero should be able to see from the get-go that the Candelabrum has seven candle holders, so display it as "(x/7 candles attached)" instead of just "(x candles attached)".
Allow the numeric prefix to work on the zap command. When zapping with a prefix specified, you will try to zap the wand that many times. (This is for easier wresting).
If you are killed by a tame monster, the death message reflects that. Perhaps as simple as putting the word "tame" before the monster.
Level teleport traps' message "You are momentarily blinded by a flash of light" should be changed or removed because it is the same message as the more dangerous magic trap effect, and it doesn't actually cause blinding.
Instead of storing door traps as part of the door state, use the trap field of struct lev with a special new DOORTRAP trap to indicate that there is a trap on the door space.
Players' thrown items should, if they miss a monster, continue flying behind it. (It works this way for monsters.)
Allow the player to dip into adjacent pools, as this is not actually hard to do in real life.
The game prints a message "You escape the dungeon, never to return again." when you escape the dungeon, instead of just going straight to DYWYPI.
If the player shoots or zaps something and there is a submerged or hiding monster the player doesn't know is there in the way, it just flies past without interacting.
Disallow quivering things that can't be used as missiles (and therefore have no business being in the quiver).
When you're helpless for more than 1 turn, the game tells you exactly how many turns you missed.
Allow all ranged attacks to be smite-targeted (that is, you choose a square within a range, not necessarily in line with anything, and your attack will hit that space under normal circumstances). In the smite-targeting UI (can generalize this to things like jumping), the path traveled will be background-hilited.
Stealing items as a monster with a stealing attack shouldn't be part of a regular attack, or else it shouldn't be possible to make a "normal" attack and also steal something in such a polyform.
Whenever a follower monster follows you between levels, print an appropriate message, such as "The wraith pursues you down the stairs." and "You are surrounded by a shimmering sphere! The Wizard of Yendor grabs your arm as you vanish!"
Add a Japanese translation for kelp frond: "nori".
Fix the "Farewell" ending message to say "turns" instead of "moves", since it's more accurate.
If you fall into water with teleport-at-will and have some way of not drowning immediately (like climbing out), the game asks you if you want to attempt a teleport spell.
When you fail to polymorph and get the "new man/woman" message, prior to this print a message that makes it clear that the polymorph fails.
Add Dudley to the list of random ghost names.
All eggs display their size, which is the same as their monster size. Chicken eggs are small. Could also change the egg weight to match.
Allow magic fountains to be specified in des files.
For TDTTOE, you only receive a "telepathic" message from your quest leader if you actually have telepathy. Otherwise, you merely "sense" the message.
New #terrain mode that highlights spaces that are known not to have traps, or if that is too complicated, that you or a pet have stepped on (can show these differently).
Review objects that are oc_big. Certain ones like chests and large boxes don't count as big, but should be.
When starting or resuming the game while hallucinating and during full moon, replace "You are lucky! Full moon tonight." with "You're on the moon tonight!"
Nagas should only be MZ_LARGE, not MZ_HUGE.
Add a new damage type AD_CHOK, for specific suffocation attacks (so that rope golems' AT_HUGS AD_PHYS combination doesn't have to be interpreted as choking).
Add a message for when your pet falls down a trap door and you don't see it happen.
An option to disable Japanese item naming.
If flags.verbose is false, replace "A mysterious force prevents [monster] from teleporting!" with "[monster] shudders briefly."
Engravings are visible from a distance. Instead of the floor rendering as . it renders as " for dust engraving, " for floor engraving, " for burnt engraving, " for a message scrawled in blood or marker, and " for graffiti. Only displays on top of floor spaces; engravings on top of other terrain don't render.
Paranoid eat option, which makes you have to type yes for "Continue eating?"
Command in the options menu that saves your non-default, non-duplicated options to an autogenerated config file, or appends them to your existing config file, or writes out a config file with the wrong name and location (so you can copy and edit it).
For variants that implement terrain recoloring while hallucinating: Don't select the color randomly. Instead use Perlin noise or other continuous noise so that contiguous regions will have the same colors.
Blessed object detection shows (item carried by a monster) for any object which is currently being carried by a monster, instead of just (item).
Rename the potion of restore ability to "potion of restore attribute".
Option to always prompt the user to "Call a [item]:" whenever it would normally be prompted as long as the item is not yet fully identified, even when it's already been called something.
A .nethackrc parse error that appears when your nethackrc does not contain a newline at the end.
The xlogfile saves the spot on the high score list that you achieved at the time the game ended.
If you try to go up or down stairs or enter a magic portal, and there is a pet that is still eating next to you, you are prompted to confirm changing levels. Also remove the "foo is still eating" message since it will then be covered in the prompt.
Remove the ability to wish for general items such as "scroll" or "ring", since more often than not these only get used when someone typoes "scroll of identigy" - people almost always *want* to wish for specific items.
If scare monster is not formally known, change "The scroll turns to dust as you pick it up" to use the called name or label.
The wish parser should accept "recharging" as a valid variation for scroll of charging.
The prompt for blessed genocide only accepts single-character strings; specifying a species won't work.
Add "choose" as a pettype option, which prompts you to select from the available pets during character creation.
Watchmen that you chat to on the Tourist quest give special dialogue themed to the Ankh-Morpork City Watch.
Donating more than 100 gold to a priest but still less than the required threshold to actually get anything causes the priest to say something gracious, rather than "Cheapskate".
Add the turn a pet was created into the edog struct, so the game can measure how long and loyal of a relationship you have with it.
Option to invert the colors of liquids, so the dominant color of the character glyph is the liquid color.
If you can see a monster only with telepathy, you cannot see its peaceful/hostile status, so all monsters appear hostile by default (except tame monsters, which you can still see as tame). Likewise, you can't see the monster names of non-tame monsters you can see only with telepathy.
If you sit on a towel, give the YAFM "It's probably not a good time for a picnic..."
The discoveries list tracks every item type you've ever held and seen, whether or not you ever type-named it.
Treat the vibrating square (if detected) as a dungeon feature in the overview, so that the level is shown as having a vibrating square on it.
New exclamations for peaceful monsters getting mad at the player when they attack another peaceful: "Hey!" "Stop that!" "Get [him/her]!" "Oy!" "Jerk!" "Try me instead!" If hallucinating, add "Dude! Not cool!" to the pool.
Untrapping a chest, whether or not successful, silently reveals the locked/unlocked state of the chest.
If you try to dissolve iron bars with acid, but it fails because they are non-diggable, there should be a message "The iron bars hiss quietly but remain intact."
When a monster that you can see becomes awake, you get a message like "[monster] wakes up" or "[monster] is roused."
Tiles for artifacts.
In the C call menu, allow \ to be entered as an alias for d, the discoveries list.
Add an option to re-allow statues to be displayed as `.
Show basic summaries of any pets with you when your game ends. Things such as their inventory, age, basic stats, whether they were a starting pet, etc. This is primarily so that it carries over into the dumplog.
When choosing a destination square to travel to, hilight the path the game has chosen to travel there.
Give a message when a wand of secret door detection reveals something.
If you select a travel destination with the _ command that the game cannot find a path to, run pathfinding a second time, this time considering unexplored terrain as eligible. If there is an eligible path running through unexplored terrain, try to move along it; if not, do not move at all.

Miscellaneous

At some skill level (Skilled or Expert or maybe even Master) martial arts gives you two attacks.
If your legs are unwounded and free, Skilled or better martial arts has a chance of dealing a kick instead of a punch. This has a small to-hit penalty but has better damage. If you want to always punch, you can either attack with F or set an option which prevents you from kicking.
Rangers have a role bonus which decreases the overall probability a projectile will break.
You can scare off the Vault guard by telling him your name is one of the demon lords. This has the same effect as if you couldn't say anything, so you're still trapped in the vault after he flees. -1 alignment penalty for lawful lying still applies.
Amnesia makes you forget spells and lose skill points instead of forgetting discoveries and maps. Normally, spell recall is drained; if a spell is at 0%, it is completely forgotten.
Some object that you can dip in lava to enhance its properties.
Hitting monsters that have a passive shock attack with something made of copper, silver, or gold increases the amount of shock damage.
When you get a wish from a water demon, it uses the cursed/unlucky wish logic because you're making a deal with a demon.
Elven priests start with an elven shield instead of a small shield.
Boulders falling on the player's head deal more damage than they currently do, and they don't really have their damage significantly reduced if the player is wearing a metal helmet.
The cost of breaking a shop door is at least partially non-deterministic, so you can't figure out the exact amount the shopkeeper will demand in advance.
After some point in the game (perhaps when you descend below the Valley of the Dead and first "enter Gehennom"), you can no longer buy protection.
Eating a chameleon corpse has a chance of conveying intrinsic polymorphitis.
Only knights of XL 7 or higher can dip for Excalibur; but Excalibur is available as a lawful sacrifice gift.
Some YAFMs for pythons should be added, both Monty Python references and jokes about the Python language.
New role: the Debtor. You begin the game by having taken out massive loans to buy a lot of very nice (erodeproof, high enchantment, magical) equipment, and so you should be able to breeze through the first part of the game. However, from time to time, your creditors appear and demand large sums of gold as interest payments. If you can successfully find enough gold to comply with their demands exactly, your debt will never actually increase. If you can overpay, you will be paying off the initial loan amount, and hopefully will eventually pay it all off. However, if you cannot meet their demands, they will first disappear with threats and take any current gold you happen to have, then send repossession men to confiscate your equipment (they will sell it for far less than it's actually worth and not really help to reduce your debt all that much), then send thugs to kill you.
If you are wielding a shatterable non-artifact and you are hit by a force bolt, whatever you are wielding is shattered.
When you fall asleep, you take d3 damage from falling to the floor.
Ghosts do not count as undead; they're just dead.
Valkyries always behave as if they were wearing snow boots while walking on ice (i.e. they never stumble).
Petrification sources need to be made more consistent - logically, "The chickatrice touches you!" should have the same effect as touching its corpse, but instead it is a mere 1/30 chance to start a delayed petrification.
Gnomes get permanent (or racial-XP-level) detection of gold and gems within a radius 3. Or possibly the radius can scale with XL.
All thrones are considered historic and Archeologists get an alignment penalty for making one disappear.
If you have swimming, you can use , to pick items up from underwater.
Stat shuffling through self-polymorph should be slightly biased towards reducing stats.
Being satiated abuses wisdom for Samurai (at the same rate it does for Monks currently), and gives Monks slow alignment penalties instead of abusing wisdom.
"while already on Charon's boat" is appended to the death message regardless of whether the player quits, if the game ends with their own role genocided.
If you're being hugged or grabbed by a monster, you can't engrave anything.
Doors are much less likely to resist when trying to close an open door.
Sokoban is undiggable until the level is solved (so monsters can't zap digging and create new holes in the floor).
Monks start with potions or a wand of enlightenment.
The chance of finding a secret door relates to how many known tiles are surrounding the door.
If polymorphed into a strong clawed monster like a dragon, you can make semipermanent engravings with "-". However, if your form does not have hands, this will be slower than an athame or wand of digging can do.
Water turbulence doesn't affect your movements unless the water square you are in is orthogonally next to another water square.
Inventory wetting triggers every turn you are submerged.
Change gravestones to CLR_WHITE instead of gray to help distinguish them from walls.
If you deliver a staggering blow or other knockback to a cockatrice, and there is a monster behind it, that monster might get stoned.
Automatic searching triggers standard 1-radius searches even when the player is blind.
Teleport at will shouldn't be gained at different experience levels for Wizards versus everyone else - it should be standardized at the same level for all characters.
Minimize the impact of enhancing a skill. Effects that changed with the threshold should be migrated to scale directly with practice as much as possible. If you have maxed a skill to its next enhancement threshold but haven't or can't enhance further, further practice is not counted.
When you first pick up the Amulet of Yendor, you get another screen-overwriting message similar to what happens in the quest and at the beginning of the game, directing you to travel back up the dungeon and give it to your god.
One-and-a-half-handed weapons that are capable of being used either one-handed or two-handed. They default to two-handed if the player is not wearing a shield or twoweaponing. They have better damage stats than pure one-handed weapons, but the damage is reduced if it is used one-handed.
Monsters only give experience points when they are at least a few levels below your own level (i.e. you can't level up from level 12 to 14 by killing only newts and grid bugs with any amount of grinding). To compensate, the cutoffs for experience level are brought closer together.
Add a joke oracularity about woodchucks.
Add the "necrotic" damage type from D&D, so that evil monsters can deal corruptive or decaylike damage without resorting to death, draining, or disintegration.
If the demigod flag is set, increase the speed of all non-sessile monsters (by giving them extra movement points).
Attacks that light things on fire also light things on the target square on fire.
Rebalance early-game monster base XP; a lichen should not be worth 4 times as much as a jackal.
If you are turning to stone and take acid damage from any source, the stoning is stopped.
Jumping costs your entire average speed's worth of movement points, not a single action.
Conflict doesn't work if a monster can't see you.
The usage fee for reading a book in a shop is reduced to 45%, to make it so that unless you have very high Cha, it's better to pay the usage fee than to buy and resell.
Archeologists can give artifacts to Lord Carnarvon. At the end of the game, any artifacts in his inventory count towards the game score, without having to drag them up to the Astral Plane.
Increase starting HP for all characters by some constant amount.
When you have glowy red hands from any confuse monster source, you can zap - (bare hands) to "zap" one charge of confusion in a direction.
The player gets a small to-hit penalty when nauseous.
If you aren't wearing armor or a shield and have high martial arts/bare hands skill, you get an AC reduction (probably mught better for martial arts).
You can't safely wear more than N total points of enchantment on all your armor at once. More than that, and armor pieces may start randomly exploding.
Add a "MumaKill" T-shirt or graffiti message or something similar.
Walking up stairs exercises Strength.
The player can instruct pets to wait in one spot and not move until summoned.
The player can shove things, dealing no damage but pushing the monster back. The monster can resist and fail to be shoved; it will resist harder if the terrain opposite it is hostile. You can only shove if you have hands, and you cannot do it to small or tiny monsters. Possibly an AT_SHOV attack should also be introduced for monsters to shove the player.
You must have at least one free hand to zap a wand. Otherwise the game won't let you.
If your character is male, a small percentage of AT_KICK attacks deal double damage to you.
Before you have u.uevent.gehennom set, demons and undead (chosen from the graveyard monster algorithm) continually spawn in the maze on the right of the Castle and try to path towards the upstairs. Also before it is set, in the Valley, awake demons and undead will try to path to the upstairs if they have nothing better to do.
Some special minor effect if you are wearing an ornamental cope as a Priest.
Assuming unicorn-gem interactions are dropped or otherwise made alignment-agnostic, remove gray and black unicorns entirely, and leave white.
Disable multishot if the player is shooting point-blank.
Greasy fingers override cursed weapons' welding themselves to your hands. This allows you to get greasy fingers intentionally to get rid of a cursed weapon.
When you hit a tree with fire from any source, it can turn into a burning tree (#). This burns for a few hundred turns before burning out and turning into normal floor. While on fire it acts as a light source of radius 9, and deals fire damage to anything adjacent each turn and occasionally to anything within a radius of 3. Come to think of it, there could also be a "bonfire" terrain using the same glyph.
Being attacked while asleep doesn't have a random chance to awaken you, but instead it reduces your remaining sleep time by some amount.
Explore mode characters start with 5 blessed scrolls of identify.
Wizards start with several random scrolls, rings, potions, and wands identified on their discoveries list, but don't actually have them in starting inventory.
When the player arrives on a newly generated level, any monsters within a certain radius of the player are randomly relocated somewhere else.
T-shirt message or rumor discussing gas spores and blasts. Possibly "Hanging out with a gas spore can be a real blast!"
Disfiguring poison that drains Charisma.
You can't ride clinging monsters (how would you get onto them, or stay on them?).
A fleshed out #chat system that would allow you to do lots of things like trade peacefuls for items, pacify and possibly even tame intelligent monsters. Intended for some future taciturn conduct, which first requires there to be actual reasons not to be taciturn. Certain monsters may also dispense random rumors as gossip.
- And with such a taciturn conduct, change messages like "You scream in agony as your body begins to warp" to YAFMs if you have kept the conduct.
When you kick a door that is closed but not locked, it can just crash open and become an open door instead of breaking. This is only if you kick it in one specific direction, deterministic based on its coordinates. Diagonal kicks can count as kicking in that specific direction, but kicking perpendicular or opposite will result in the door breaking like usual.
Priests can hit incorporeal monsters like shades by default. Their attacks never pass harmlessly through.
Trees can rarely drop slime mold "fruit" when kicked.
Levelporting to a level you have never visited may fail and levelport you randomly (except in wizard mode). If you have previously visited the level, levelporting will place you in a spot that has been previously mapped.
Assuming empty potion bottles are somehow implemented so as not to be game-breaking: they should weigh 1 or 2 aum, and can be dipped in sinks to fill them from the faucet. This usually fills them with water, but can have other sink effects such as getting a random potion from the faucet instead.
Wielding a one-handed weapon with no weapon in the offhand will double the damage bonus from Strength (but not weapon damage or other bonuses).
Vomiting subtracts nutrition proportional to your current nutrition.
Barbarians get a little extra nutrition from eating corpses, since they have practice in how to eat them properly.
Nymph race very similar to dNetHack's yuki-onna, but based on regular NetHack nymphs (so no association with cold, no iron weapons). Copies the unarmed attack automatic stealing yuki-onna ability, and has infinite carry capacity, but low HP.
You can mail-order items and have them delivered to you some time later by the mail daemon.
Make the Oracle consultation prompts more obvious as to what they're getting. "Dost thou wish to hear the latest dungeon gossip?" / "Dost thou desire a serious piece of advice?" Also, it should prompt the player even if they have no money.
Role which is outsizedly powerful in the early game and can tear through the dungeon easily, but has a much harder late game, perhaps enforced through bad skill caps (no Expert), or bad HP growth. Or can't use most artifacts, or has obstacles to putting together an ascension kit.
It gets increasingly hard to raise a stat through exercise as the stat approaches its racial maximum.
Birth option in which you spawn as a zombie of your regular race instead of just that race.
If you fall asleep while having astral vision, you get astral projection. This consists of you spawning as some sort of incorporeal monster which can phase next to your body. Your body can't move. Your projection can use your items like normal (consumables and charges are used up). If your projection dies, you return to your body and sleep out the remaining duration. If you wake up, your projection is destroyed and you return to your body normally; however, combat will not awaken you. If something else kills your body while you're projected, you die and the game ends.
If the player can displace peaceful monsters, hostile monsters should be able to as well.
Track your maximum reached HP and Pw (or maximum "external sources" HP and Pw if using a system where it mainly depends on a stat and XL) and allow restore ability to also fix these.
Alternate ending where you can settle down in an abandoned temple or possibly just a random altar room and become the priest of the temple permanently. (Creating a bones file where you are now an aligned priest).
You can force-fight a web to cut it, which may occasionally fail and get you or the weapon stuck in the web.
Archeologists begin the game with a grappling hook.
Remove the unidentified appearance of "grappling hook" as "iron hook", it's confusing and serves no good purpose.
If you are hallucinating, replace the message "You can't fight yourself." with "You can't come to terms with your inner conflicts."
You can use #force to pry open doors with edged weapons; however, this requires more Str and has a higher chance of breaking the weapon (perhaps dependent on the weapon's weight.)
Role or race that gains a bad intrinsic at a certain fairly low XL, and a very good intrinsic later.
If you die next to a pet that can make you arise from the grave, it infects you and makes you arise from the grave as that, without ending the game.
Add as rare possible fountain effects erodeproofing and blessing a dipped object. (Possibly only in magic fountains.)
If you are not deaf, non-stealthy monsters that you can't see (because they're out of sight or invisible) occasionally show up as an I when they move. Blindness has no effect, except indirectly that adjacent spaces also count as out of sight.
Only allow levelporting to go out of a branch in the "direction" it rejoins the parent branch. The main reason for this is so that anything levelporting out of Vlad's Tower cannot end up on levels above the tower; only on levels lower than it.
Every turn on the Plane of Fire, all scrolls and spellbooks in inventory or on the level are destroyed (except for naturally fireproof ones).
The passtune can be played at any drawbridge in the game to open or close it, but only the Castle drawbridge gives feedback in the form of gears and tumblers. You have to learn the passtune there in order to feasibly use it at other places.
Gnomes (or a potential Tinkerer role) can loot statues without destroying them.
Occasionally when suffering from food poisoning, you vomit, which will then save you from dying (but still remove a lot of nutrition which means you're probably still in some peril).
Replace the existing polyself nerf that 20% of polymorphs turn you into your own race. Instead, have it so that the longer you stay polyed, each successive polymorph has a shorter duration. If you stay in your normal form for a while, polymorphs will return to their original duration.
Paralysis only freezes you in place on a square; it doesn't prevent you from attacking and taking other non-movement actions.
Make the Vibrating Square a brighter color than purple.
You can occasionally get a free food appraisal when you eat something. This is based on a random number computed from the turn and (possibly) the object ID, weighed against your Wisdom somehow, such that higher Wisdom increases the chance that you get the food appraisal.
If trees' fruit is ever made deterministic to the tree, occasionally scatter some of that fruit around the base of the tree.
Apply the digging-a-grave-up behavior (summoning undead, alignment penalties, etc) when a headstone is kicked over, as well as digging it up. (The "unearth a corpse" behavior would be to bury it underneath instead.)
Archeologists begin the game able to recognize all eggs.
The chance of you catching lycanthropy is boosted on a full moon and zero on a new moon.
Being strangled for more than a couple turns starts to reduce your Constitution (or maxHP).
Pushing a boulder costs d3 or d4 nutrition, in order to balance out its easy source of Str exercise. However, something would probably need to be done to compensate in Sokoban (maybe put even more food there?)
Track how many turns the hero has spent on a level. As they spend more time there, the monster spawn rate diminishes, provided they aren't in the end game with its special spawning rules.
Addendum to the brewing patch: you can ferment/dissolve newt corpses to produce potions of gain energy, and can combine various fruits with water to produce fruit juice. Also, since booze tastes like liquid fire, fermenting a red mold corpse produces a potion of booze.
Non-excessive luck system: start by disentangling luck and religion, and convert rnl checks into other checks. Luck can only be -1, 0, or 1 and can never time out unless a full moon or Friday the 13th ends. Some things can reduce Luck to a base of -1, but nothing can increase it to a base of +1 other than carrying positive luckstones.
Things that can curse, steal, or change your name in-game.
Extend Cleaver's wide-arc hitting behavior to all battle-axes.
Dipping a weapon into a fountain can as a random effect raise its enchantment by one, to a maximum of +1.
If you have previously died and gotten lifesaved in the game, some things or people interact with you differently.
Allow human Rangers to play as lawful.
Tourists begin the game with 1 or 2 Luck.
Barbarians who roll a 1 on their damage die get the die rerolled and the second result used.
Cursed or unlucky wishes for scrolls, potions, or spellbooks may give you the blank counterpart instead of what you wanted.
Different roles have different speeds for putting on armors.
Kicking a tree may cause you to get hit by a falling branch and take some damage.
Some mechanic for Valkyries that involves escorting the spirits/ghosts of those who die in battle. Would probably interact with nethack ghosts the best.
Add "magical writing" as a nonweapon skill, which is trained really fast by writing scrolls and spellbooks, and increases your odds of writing unknown scrolls and spellbooks successfully.
Every role has a small set of monsters that it can tame through non-magical means (such as Valkyries and winter wolves).
Speed system overhaul: Every 12 turns, a monster populates an array of 12 bits, setting (speed modulo 12) of them to 1 and the rest to 0. A monster's moves on a turn are (speed / 12) rounding down, plus another 12 if the bit on that turn happens to be 1.
A trap or monster (or possibly change sleeping gas traps or homunculi to this) that causes "sleeping poison": it starts a very short intrinsic restful sleep timeout, so you don't fall asleep immediately but have a little time to react.
A role or race whose gimmick is to continually lose Constitution points every couple hundred turns; going below 1 (or 3?) results in death.
Some mechanic (possibly a ritual spell) that enchants gems by disenchanting other items. Once enchanted, a gem can be used a single-use Pw reserve, magical grenades, or (rarely and lossily) tranfer their enchantment into some other piece of gear. Gem enchantment rules follow ring enchantment rules with respect to exploding when they get too full of magic.
An alternate ending triggered by invoking a ring of conflict when within sight of all three Riders. You then take up your true identity as War and the other Riders congratulate you. Possibly tie this into the "break the Amulet" ending, in which case this would massively power you up but not end the game until some other condition had been met.
Add a hard cap on the amount of levels you can gain via foocubus, but count each level gained this way - each 'educational experience' - as +1 on your chance towards a good outcome of future interations.
Intrinsic aggravate monster from eating dogs and cats lasts for a few thousand turns; actual cannibalism lasts many thousand turns, but neither gives it to you permanently.
When you're brought below 20 HP and also below 10% of your HP, with no status ailments, a special adrenaline buff automatically kicks in that grants to-hit and damage bonuses for a short time, but causes exhaustion debuffs after it times out.
Kicking a wall where there is a secret door will always reveal the door and will never hurt you. This first kick may WHAMMM or crash it open as usual for doors.
Allow "You hear someone counting money" to show up on levels with no vault but which do have a shop.
Traits or feats, selected when you create your character, and give you small buffs in the form of slight or situational effects. Buffs could include:
- Small increases to your maximum HP and Pw pools.
The closer someone is to iron bars when attempting to shoot ammo through them, the lower the chance is of it hitting the bars.
Break the fumbling intrinsic into fumbling (only for hand-related things, conferred by fumble gloves) and stumbling (only for foot-related things, conferred by stumble boots).
Archeologists and Tourists get experience for photographing monsters they haven't yet photographed.
Add a NAME: directive to the level compiler. Levels that have this will auto-annotate themselves as such (or add an immutable line with the name) once the level is entered.
Monks who have passed through all the "Student of X" titles may go back and speak to the Grand Master to choose an elemental specialization and receive a power related to it. Stone gives a physical damage reduction; Air gives a random extra movement point here and there and a rare chance of dodging an attack. Water automatically counterattacks melee attacks. Fire boosts attacking power or gives extra attacks.
Intrinsic telepathy only works in a radius equal to your Int (extrinsic sources aren't changed). Co-op telepathy is in the same radius if intrinsic, full-level if extrinsic.
Scare system that works on the player: the game tracks a list of monsters (or monster IDs) you are currently scared of and for how much longer you are afraid of that monster. You cannot attack a monster you are scared of in melee, nor can you use a ranged attack towards it when you can detect it in the line of fire, nor can you move directly towards it. (Trying to do any of these things won't cost a turn.)
Special damage type AD_GNAT: when hit with it, you are compelled to attack the offending monster on your next turn if able. (Or as a weaker version, you can do things other than attack, but if you want to attack you must attack the offending monster).
Your hunger rate is halved when you are asleep.
Rangers have a special bonus towards searching for pits.
Add a new ending where you take the unused wand of wishing from the Castle and exit the dungeon with it, to give to your deity to help the next chosen hero. This counts as an honorable ending and a win.
When you fall into water, you can choose the adjacent space you climb out on.
Give a warning message when temporary speed is about to wear off.
Assuming a player-side fear effect is implemented, booze provides immunity to this fear effect for as long as the Confusion continues.
If you have confusion charges from the scroll or spell (meaning your hands are glowing red), the Z menu will gain a "confuse" spell option that always has a 0% failure rate. Casting this allows you to "zap" a confusion charge in any direction, confusing the first monster it touches.
Some mechanic that allows you to capture a defeated monster as a figurine (inspired by SpliceHack's cartomancer but not tied to a specific role, and also not as easy to come by, probably requiring special magic or a special tool to perform it).
Assuming an implementation in which Gehennom starts to get destroyed after you remove the Amulet: When you kill the high priest of Moloch, he gives you a multiline death message calling you a fool and saying you don't know what you have done, and maybe hinting a little bit at why Hell is about to go to hell.
Add a random throne effect that polymorphs you into a level-appropriate royal monster.