Dungeons of Doom

The Dungeons of Doom is the name given to the first half of the Mazes of Menace. They are 25 to 29 levels deep and contain a number of special levels and the entrances to several branches as well as the majority of special rooms and random dungeon features.

The player starts on the first floor of the Dungeons of Doom and has to work their way down, eventually passing below the Castle into Gehennom. After retrieving the Amulet of Yendor from Gehennom, they must then return to the first floor, and climb the stairs to enter the Planes.

Structure

• The first level of the Dungeons of Doom is always at dungeon level 1.
• The entrance to the Gnomish Mines appears on levels 2-4.
• The Oracle level appears on levels 5-9. The entrance to Sokoban always appears on the level following the Oracle.
• The Big Room has only a 40% chance of appearing, but if it does, it appears on levels 10-12.
• A magic portal to the Quest appears on levels 11-16.
• A magic portal to Fort Ludios can appear in a vault anywhere after (but not on) level 10.
• The Rogue level appears on levels 15-18.
• Medusa's Island appears 1 to 4 levels above the last level of the Dungeons of Doom. This means it can appear anywhere from level 21 to 28.
• The Castle is the lowest level of the Dungeons of Doom, on level 25-29, and connects to Gehennom.

Random dungeon levels

All levels in the Dungeons of Doom that are not special levels generate with a network of rooms connected by corridors, and are sometimes referred to as room-and-corridor levels (although this term is also used for filler levels in some Quests which do not use the same algorithm, since they are technically special levels). Rooms are typically, but not always, connected to the nearest rooms left and right of them.

Closets

On each level, a number of closets generate; this number is anywhere from 1 to half the total number of rooms on the level. Closets may have an obvious door, a secret door, or no door at all.

Special rooms

On levels 2 and below, one room per level may be converted into a special room. Independently of this, a level may generate a vault unconnected to the rest of the level.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.

Themed rooms may also generate on these levels; these typically do not involve special rooms, but add the possibility for unusual terrain, monsters, or objects to appear that would not ordinarily.

Normal room contents

Each ordinary room generates the following contents, in this order:

• ¹⁄₃ chance of a single random monster. If the monster is a giant spider, a web and random object will be placed on its starting position. If the monster is of a type that normally generates in groups, this is suppressed and it generates by itself.
• Zero or more traps. Multiple traps can be placed in a room; if one trap gets placed, the game tries again with the same probability and continues doing so until the chance finally fails. The chance of traps starts at ¹⁄₈ per room, but increases with greater level difficulty.
• ¹⁄₃ chance of a pile of gold, the quantity of which correlates to the current dungeon level. It is typically a very small amount on early floors.
• ¹⁄₁₀ chance of a fountain.
• ¹⁄₆₀ chance of a sink.
• ¹⁄₆₀ chance of an altar, which will not be a temple nor have a priest in attendance.
• Zero or one grave. The chance of a grave starts at ¹⁄₈₀ on dungeon level 1, but increases to ¹⁄₇₈ on level 2, ¹⁄₇₆ on level 3, and so on.
• ¹⁄₂₀ chance of a statue of a random monster.
• ²⁄_{(5 * total rooms)} chance of a container with random contents. The container will always be a large box (²⁄₃ chance) or chest (¹⁄₃ chance).
• Zero or one graffiti. The chance starts at ¹⁄₂₇ on dungeon level 1, then decreases to ¹⁄₃₀ on level 2, ¹⁄₃₃ on level 3, and so on.
• ¹⁄₃ chance of at least one random object. If an initial object generates, there is a successive ¹⁄₅ chance of another object generating, which keeps being re-rolled until it finally fails.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.

Levels in the Dungeons of Doom now generate "bonus items" intended to help the player in the early game. These items generate in one randomly chosen room per level, occurring just after statues generate. The room is always one which is eligible to receive normal room contents as described above, which includes ordinary rooms and some themed rooms that lack special features.

If you are on the level with the stairs to the Gnomish Mines, one room on the level will generate an additional comestible. This will be a food ration (60% chance), cram ration (20% chance), or lembas wafer (20% chance).

If you are on a level above the Oracle, with ²⁄₃ chance, one room on the level will generate a special "supply" container with the following properties:

• It may be a large box with ¹⁄₃ chance, or a chest with ²⁄₃ chance.
• It is never trapped, but is locked ⁵⁄₆ of the time.
• It always contains at least one "helpful" item.
  • 50% of the time, this is a potion of healing (and when it is, there is a further 50% chance that there is a stack of 2 potions).
  • The remainder of the time, an item is randomly selected from the following list: potion of extra healing, potion of speed, potion of gain energy, scroll of enchant weapon, scroll of enchant armor, scroll of confuse monster, scroll of scare monster, wand of digging, spellbook of healing.
  • There is a successive 20% chance of generating another "helpful" item, or 100% if the item just generated was cursed, using the same formula.
• Then, there is a ²⁄₃ chance of generating a random item.
  • There is a 30% chance the random item will be a spellbook which is not a novel. If so, the spellbook will be biased towards being low-level by taking the lowest-level of 3 random spellbooks on dungeon levels 1 or 2, or the lowest-level of 2 random spellbooks on other levels.
  • Otherwise, the random item will be one of the following: comestible, weapon, armor, gem, scroll, potion, or ring.

Based on the contents of such a container, it may be possible to deduce that it is a supply chest, and infer additional things about its contents.

Random maze levels

If there are levels between Medusa's Island and the Castle, there is a 20% chance that each level will generate as a room-and-corridor level, but the remaining 80% of the time they will generate as a maze.

References

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"Changes to the dungeon in variants maybe?"