Room Generation

On levels that generate rooms (normal type, city type, single monster type), certain rooms can have special properties. These levels generate 7d2-7 special rooms.

To generate a special room, first the type of the special room is chosen. Then, a room is chosen to have the special feature. Some features have a requirement on the dimensions of the room. If no valid room exists, the placement of that particular special room will be skipped. There can only be 1 special feature per room.

The probability of room types is the same for normal and city type maps, but is different for single monster type maps (in particular, no vaults are generated).

¹: Fluid rooms have an additional requirement on size described below.

Here, dimensions include the walls of the room.

The special rooms are described in detail below.

Fluid Rooms

A fluid is completely filled with a fluid. The fluid is determined by a roll of 1d10 + floor(dlevel/5).

Rooms cannot be filled with fluid if their area is greater than 120 (including the walls).

Ammo Rooms

Ammo rooms contain additional ammunition beyond what is generated by the normal item spawning procedure. The type of ammunition is all the same, with the type determined by a roll of 1d3 + dlevel.

The number of stacks of ammo is 1d3 + 2.

Teleporter Rooms

Teleporter rooms contain a teleporter. Teleporters cannot be placed unless they are adjacent to 3 floor tiles. In particular, they cannot be placed in hallways of width 1.

Lever Rooms

Lever rooms contain a single lever placed at random. The lever type is randomly determined. The number of charges is also random.

Several of the lever types have a chance of affecting the entire level. This determination is made when the lever is generated, and when it happens, a special level feeling occurs. These levers and their associated data is below:

Vaults

Vaults contain extra items and monsters beyond what are generated by the above procedures. These monsters and items do not count against the limits described above. Each vault on the level generates a feeling, one of You feel excited!, There's the smell of blood in the air!, and There's something special here... uniformly at random.

The layout of a vault is unusual. A vault contains an inner room that takes up its entire space except for a path of width one all the way around it. There is a single door to the inner room.

The difficulty of the monsters and the quality of the loot are determined by a single roll of max(1d5 + dlevel + (difficulty - 2) * 3, 1).

The monster type is determined as follows:

If the roll is at least 30, a nightmare monster might be used instead depending on the roll modulo 6. If the roll modulo 6 is 3, nightmare imps are used; for 4, nightmare cacodemons are used; for 5, nightmare demons are used. (This calculation has the unusual side effect that some enemies will never be generated for certain combinations of dlevel and difficulty, even for high dlevel.)

The number of monsters spawned in a vault depends on the difficulty level.

The number of items spawned in a vault is 1d3+2. These items are chosen from armors (not boots), ammunition, ranged weapons, and packs. Packs refer to all items that appear in the use menu including mods and reusable unique items. The items are selected from the list for dlevel = roll+3. (This is always higher than the normal dlevel.) Also, weights of unique items are doubled.

Sometimes vaults can be locked. A locked vault must choose an auxiliary special room that is at least 4 × 4 tiles large with an empty tile. If such a room exists, then there is a min(dlevel - 1,25)/100 chance of a locked vault.

A locked vault has no door to its inner chamber, and the walls of the inner chamber cannot be destroyed by weapons. Instead, a "destroys walls" lever is created in the auxiliary room that removes the inner chamber walls of the vault. This key lever cannot be destroyed by explosions.

In locked vaults, the weights of unique items are tripled.

For small vaults, it is important to note that monsters are placed before items. It is possibles for too many monsters to fill up a vault and reduce the number of items inside, especially on high difficulty levels.