Player's misconceptions

This article attempts to dispel common assumptions and misconceptions that many players may have about NetHack. This is not to be confused with misconceptions that NetHack players may have about other variants of NetHack (or vice versa) or even different versions of the same game, which is generally referred to as "variant paranoia".

NetHack is not real life

A root of many such misconceptions that players develop regarding NetHack and its mechanics, particularly the ones listed below, is that they often assume various aspects of the game such as a hero's nutrition should function within the game world as they do in our world. The core thing to remember is that, while some aspects of the game may draw from real life, NetHack is not real life: mechanics within the game will not always reflect real life, and are under no obligation to—in some cases, this may even be for the better.

Nutrition

Drinking water is necessary

Water is not necessary for a hero's survival. The Guidebook's advice on this matter is misleading, stating that "although creatures can survive long periods of time without food, there is a physiological need for water"—while true for real life, it surely does not apply for the hero in NetHack, and not only is there absolutely no need to drink water at all, but quaffing water from fountains can be downright dangerous (to speak nothing of sinks).

Because corpses are dangerous to eat, they should be saved for emergencies

Some corpses are indeed inherently dangerous, and many of them should not be eaten. Any other corpse should be eaten while it is still fresh, if you plan to eat it at all: if you save a corpse to eat later, it will almost certainly be tainted and give you food poisoning, unless you keep it in an ice box or apply a tinning kit (both of which are vaguely analogous to real life). Lizard and lichen corpses are exceptions to this rule, as they last indefinitely.

I would not eat that in real life, so my character also probably should not

Again: NetHack is not real life. Though many of us in the real world would not eat the corpse of a sewer rat, lichen or jackal–let alone uncooked ones due to the severe risk of illness–that is not an issue for your character in the game (or indeed any other monster that eats). Therefore, if a corpse is fresh, it will probably be safe for consumption unless there is something intrinsically harmful about that corpse or the monster that dropped it, e.g. the poisonous kobold or the stoning-inducing cockatrice.

Eating pet corpses is bad

There is no specific penalty for eating a pet's corpse after the creature is already dead. However, there are bad effects for eating certain corpses in general or performing other actions with pet corpses:

• Eating the corpse or tin of a kitten, little dog or any of their growth stages will give the hero the aggravate monster intrinsic, which applies regardless of whether it was a former pet.
• Personally killing a pet incurs an alignment record penalty of -15 and a -1 luck penalty. Displacing a pet to their death also incurs a -15 alignment record penalty and angers your god.
• Sacrificing pets that have died while tame also gives bad effects including the aggravate monster intrinsic, and should be avoided.

Magic

Wizards are better at reading spellbooks

This one is more of a half-truth in practice: the formula that determines the chance of successfully reading a spellbook is the same for all heroes, and is primarily reliant on intelligence—Wizards are one of a few roles that start with quite high intelligence on average. What actually gives Wizards an advantage when reading spellbooks is that they will be warned if they have less than a 100% chance of successfully learning the spell from from an uncursed spellbook; the player is prompted whether or not they want to continue reading, which has no effect on the actual success chance itself.

On the note of role-specific advantages, Wizards are better at writing unknown scrolls and spellbooks with a magic marker than other roles.

The player should not wear metal armor if intending to cast

This is true in the broad strokes: metallic armor does hinder spellcasting while worn, but the level of hindrance depends on the armor type and the hero's role. Shields and metallic body armor tend to interfere with casting the most across the board—some casting-focused roles have strong enough spellcasting abilities that they can offset the penalty from these with a worn robe, while others can better handle metallic armor in slots besides these. For example, a Wizard with 18 intelligence can wear a metallic helmet, pair of boots or pair of gloves and still cast low-level spells with 0% failure, while only seeing a small increase in failure rate for higher-level spells.

Behavior and conducts

A chaotic hero can kill anything without penalties of any kind

Heroes of chaotic alignment take alignment and luck penalties for most of the same things that heroes of other alignments do—this includes killing co-aligned peaceful monsters or killing 'always-peaceful' humans. While those penalties themselves may not be as stiff in the case of a chaotic hero, their alignment is not license to do whatever they please and otherwise behave in a "Chaotic Stupid" manner: e.g., they are not penalized specifically for murder, but still take significant alignment penalties for killing peaceful human monsters.

See the alignment record article for more details on alignment penalties and bonuses.

Offering a human corpse is bad

It is bad to sacrifice a human corpse while playing as a human hero, unless you are chaotic. However, the nature of the penalty is not specifically for human sacrifice: heroes that sacrifice monsters of their own race will always be penalized if they are not chaotic, while a chaotic hero that does so may potentially be rewarded depending on the context.

Monster behavior

This monster is so strong, this status property won't help me

Several boss-level hostile monsters in the game are vulnerable to sources of ailments and instant deaths such as poison, paralysis and even stoning in some cases.

The concept of stronger monsters having more immunity to various types of damage and ailments was not as ubiquitous in games when the first versions of Hack were released, and even as the idea became more widespread in role-playing games over the years, it is still relatively rare within NetHack itself. Dragons and other monsters with elemental attacks or breath attacks are usually only immune to the elements of those attacks, and even the Wizard of Yendor himself is not immune to a cockatrice corpse or a wand of death! (Just don't assume that it deals with him permanently.)

The specific weaknesses of a given monster depends on their magic resistance value (or 'MR score') as well as their actual resistances, and much of the difficulty involved is in learning about these vulnerabilities unspoiled (often involving trial and error). A high MR score can also make a monster seem immune to certain status properties, due to their higher odds of resisting each time—as an example, none of the demon lords and princes are immune to a wand of sleep, but their MR score is often high enough that it can take several zaps for the effect to actually stick.

One of the few "contractual immunities" that occur in NetHack is the stoning resistance shared among quest nemesis monsters in particular: this is ostensibly done in order to prevent the Quest from being trivialized in a relatively easy manner, as a quest nemesis may still have other weaknesses that a hero can exploit depending on their attributes and the availability of certain items. Some NetHack variants may also opt to grant additional resistances or immunities to various monsters that they lack in NetHack (with particular emphasis on unique monsters), which in turn is also a frequent source of variant paranoia.

Attributes

Gauntlets of power are required to maximize carrying capacity

This is another half-truth: Carrying capacity is based directly on the hero's own strength and constitution. Specifically, the formula is ((STR + CON) * 25) + 50, and carrying capacity has an upper limit of 1000—a combined strength and constitution of 38 grants maximum carrying capacity, with strength values of 18/32–18/81 being considered equivalent to 20, and thus all races of hero other than elves can reach this maximum without the use of gauntlets of power or any other additional equipment. So while the gauntlets of power can obviously help raise this value, wearing them is only "mandatory" for elven heroes that wish to do so.