Random vault (UnNetHack)

Random vaults are a part of the level generation formula introduced in UnNetHack. The name is a misnomer: these are entirely unrelated to the hidden vaults filled with gold, and connect normally to the rest of the dungeon.

Every room that isn't part of a special level and not a vault is selected from the list of random vaults.

The "normal random room" has a 40/41 chance of being selected. All the others have a 1/2050 chance of being selected.

Some random vaults, including the "normal random room", can be further transformed into Special rooms.

In the UnNetHack source code, the random vaults are defined in dat/vaults.des.

Possible Vaults

Name	Can be special	Size	Map	Notes
Normal random room	Yes			The regular rooms found in vanilla NetHack The only one with a unique chance of being generated, (40/41 compared to 1/2050)
Fake Delphi	Subroom only	11x9		A big room with a small room in the center, similar to Delphi Both the room and the subroom are guaranteed to be lit There is a door to the subroom, with a 25% chance of a second door. Both doors have a chance of being locked and/or trapped and/or secret.
room with a subroom	Subroom only			A random room with a random subroom
big room, 1	No	30x10		Has a 75% chance of having a random normal room as a subroom This subroom will have a randomly placed door with a 50% chance of a second door Both doors have a chance of being locked and/or trapped and/or secret.
lava/ice/pool/tree/fountain room	No	3x3		The center square of the room has an equal chance of being lava, ice, pool, tree, or fountain. Each other square has a 10% chance of being the same as the center square.
big room, 2 (max. vertical height)	No	10x17		2d3 random hostile monsters
thin, long, horizontal room	No	17x3		2d3 random hostile monsters
thin, long, vertical room	No	3x17		2d3 random hostile monsters
tiny cage, big monster	No	5x5		DL1 or DL2: just a random room with a 2x2 subroom Otherwise: subroom also has a random M, D, O, Z, T, or H and the monster will now be caged in iron bars
room with dangerous monster and loot	No			Up to 3 monsters from the classes M, D, O, Z, T, or H 100% chance of the first random hostile monster 50% chance of a second hostile monster 25% chance of a third monster (not guaranteed to be hostile) These percentages are calculated independently, so there is still a 25% chance, even if the 50% chance fails. Random object 100% chance of the first object 75% chance of a second object 50% chance of a third object 25% chance of a fourth object (this one will be cursed) 10% chance of a fifth object (this one will be blessed)
Name	Can be special	Size	Map	Notes
boulder room	No			1d6 + 3 boulders 1d4 rolling boulder traps
spider nest	No			unlit 3d3 webs
ice room	No			10% chance of a cold trap Floor replaced by ice
random cloud/lava/ice/pool/tree room	No			30% of the tiles are replaced with cloud, lava, ice, pools, or trees (all will be the same type of replacement)
buried treasure	Yes			Guaranteed buried chest with 3d4 objects
massacre	No			5d5 random corpses of the following @', "apprentice", "warrior", "ninja", "thug", "hunter", "acolyte", "abbot", "page", "attendant", "neanderthal", "chieftain", "student", "wizard", "valkyrie", "tourist", "samurai", "rogue", "ranger", "priestess", "priest", "monk", "knight", "healer", "cavewoman", "caveman", "barbarian", "archeologist", "convict" Each corpse generated has a 90% chance of being the same as the previous corpse generated
statuary	No			5d5 statues 3 statue traps, each with 50% of existing
light source	Yes			unlit guaranteed lit oil lamp
potentially spooky	Yes			unlit if it's night time: 100% of first grave 20% of second grave if DL > 10, there will be a &
temple of the gods	No			one altar of each alignment
Name	Can be special	Size	Map	Notes
mausoleum	No	5x5		Equal chance of one of the following random hostile L, M, V, Z in the middle corpse of a random @ 20% of a secret door never in a corner outer tiles will be solid rock
big room, 1, random type	No	17x10		a larger version of any type of randomly generated room
big room, 2 (max. vertical height), filled with fog	No	10x17		lot of clouds 2d3 random hostile monsters
very thin, long, horizontal room	No	50x5		2d3 random hostile monsters
very very thin, long, horizontal room	No	70x3		2d3 random hostile monsters
L-shaped	Yes		-----xxx |...|xxx |...|xxx |...---- |......| |......| |......| --------	can exist in any of the 4 possible rotations
L-shaped, big	No		-------xxxxxx |.....|xxxxxx |.....|xxxxxx |.....|xxxxxx |.....|xxxxxx |.....------- |...........| |...........| |...........| |...........| |...........| -------------	can exist in any of the 4 possible rotations
Blocked center	Yes		----------- |.........| |.........| |.........| |...}}}...| |...}}}...| |...}}}...| |.........| |.........| |.........| -----------	75% chance of replacing lava with one of the following: solid rock pool of water crystal ice wall
Circular, small	Yes		xx---xx x--.--x |-...-| |.....| |-...-| x--.--x xx---xx
Circular, medium	Yes		xx-----xx x--...--x |-.....-| |.......| |.......| |.......| |-.....-| x--...--x xx-----xx
Name	Can be special	Size	Map	Notes
Circular, big	Yes		xxx-----xxx x---...---x x-.......-x |-.......-| |.........| |.........| |.........| |-.......-| x-.......-x x---...---x xxx-----xxx
T-shaped	Yes		xxx-----xxx xxx|...|xxx xxx|...|xxx ----...---- |.........| |.........| |.........| -----------	Can exist in any of 4 rotations
S-shaped	Yes		-----xxx |...|xxx |...|xxx |...---- |......| |......| |......| ----...| xxx|...| xxx|...| xxx-----	Can exist in any of 2 rotations
Z-shaped	Yes		xxx----- xxx|...| xxx|...| ----...| |......| |......| |......| |...---- |...|xxx |...|xxx -----xxx	Can exist in any of 2 rotations
U-shaped	Yes		-----xxx----- |...|xxx|...| |...|xxx|...| |...-----...| |...........| |...........| |...........| -------------	Can be flipped vertically
C-shaped	Yes		-------- |......| |......| |...---- |...|xxx |...|xxx |...---- |......| |......| --------	Can be flipped horizontally
Tetris L-shaped	Yes		-----xxx |...|xxx |...|xxx |...|xxx |...|xxx |...|xxx |...---- |......| |......| |......| --------	Can exist in any of 4 rotations
Tetris J-shaped	Yes		xxx----- xxx|...| xxx|...| xxx|...| xxx|...| xxx|...| ----...| |......| |......| |......| --------	Can be in any of 4 rotations
Four-leaf clover	Yes		-----x----- |...|x|...| |...---...| |.........| ---.....--- xx|.....|xx ---.....--- |.........| |...---...| |...|x|...| -----x-----
Cross	Yes		xxx-----xxx xxx|...|xxx xxx|...|xxx ----...---- |.........| |.........| |.........| ----...---- xxx|...|xxx xxx|...|xxx xxx-----xxx
Name	Can be special	Size	Map	Notes
watcher in the water	No			Not to be confused with the monster of the same name This room contains 1d3 random pools If this occurs on level 3 or deeper, it will contain, a Giant eel, Electric eel, or Kraken
room with sessile growths	No			4d3 sleeping gas spores, F, b, j, and P
Pillars	Yes	10x10		There is a 2x2 pillar with one of the following terrain: 50% chance of solid rock 10% chance of lava 10% chance of ice 10% chance of a pool of water 10% chance of trees 10% chance of crystal ice wall
Small tightly-placed pillars	Yes			If the width or height is even, no special terrain Otherwise, 1x1 pillars with one of the following terrain: 5/12 chance of solid rock 1/12 chance of lava 1/12 chance of ice 1/12 chance of a pool or water 1/12 chance of tree 1/12 chance of crystal ice wall 1/12 chance of cloud 1/12 chance or iron bars
Mirrored obstacles	Yes			If the width or height is below 4, no obstacles Otherwise, 1d3 pairs of mirrored obstacles, using one of the following terrain: 5/12 chance of solid rock 1/12 chance of lava 1/12 chance of ice 1/12 chance of a pool or water 1/12 chance of tree 1/12 chance of crystal ice wall 1/12 chance of cloud 1/12 chance or iron bars
Trap Room	No			Filled with traps. The number of traps will be equal to 1/4 the area of the room, plus up to an additional 1/3 of the room The traps will be selected from the following list: (pit/spiked pit) land mine falling rock (fire/cold trap) (trap door/hole) (arrow/dart)
Underground rivers	No			might not count as an actual "room" random "globs" of lava or water pools
Trapped rust monster, disenchanter, or disintegrator	No	5x5		Has a 2x2 island of hostile R, surrounded by pools of water Other than polymorph, this is the only time that disintegrators can appear in UnNetHack (thankfully)
Fern nursery	No			If DL >= 3: 25% chance of a dungeon fern 50% chance of a arctic fern 50% chance of a blazing fern 50% chance of an swamp fern
Ozymandias' Tomb	No		--------- |^.....)| |..^..^.| |....^.`| |....21\| |.......| |^.....^| |......`| ---------	The room is lit 1, burned, reads "Look on my works, ye mighty, and despair" 2, burned, 10% chance of existing, reads "My name is Ozymandias, king of kings" Each hole has chance of existing, between 30% to 80% Falling rock traps will be replaced by webs if DL >= 7 The falling rock tap/web nearest the throne is guaranteed, others have a 75% chance of existing The chest is trapped The statue trap near the throne has a statue of a werejackal The statue trap near the corner has a statue of an Elvenking
Name	Can be special	Size	Map	Notes
Pacman	No		-------------------- |....|........|....| |.--.|.------.|.--.| |.|..............|.| |.|.--.|-##-|.--.|.| |......|    |......| |.|.--.|----|.--.|.| |.|..............|.| |.--.|.------.|.--.| |....|........|....| --------------------	All of these are guaranteed at random positions: an apple a pear a banana an orange a melon a ghost named Inky a ghost named Blinky a ghost named Pinky a ghost named Clyde