Trap door
A trap door is a trap identical to the simpler hole except that it starts out hidden. When triggered, you fall to a deeper dungeon level.
Generation
Trap doors be randomly generated at any dungeon level. Trap doors cannot be randomly generated on levels with non-diggable floors such as the vibrating square level or the Castle, although the Castle contains several statically placed trap doors. If the floor is non-diggable, the trap door is replaced with a falling rock trap. Trap doors cannot be generated beneath a boulder. They are sometimes found in closets, with "Vlad was here" engraved in front of the door.
Effects
Both you[1] and monsters[2] can be affected.
Just like a hole, 2 or 3 levels is common, there is no upper limit, and you cannot fall beyond the Castle. Monsters never fall more than one floor[3][4].
Removal
Push a boulder into it.
Messages
- A trap door opens up under you!
- You activated a trap door.
History
Trap doors existed in Hack 1.0, predating holes.
Encyclopedia entry
I knew my Erik too well to feel at all comfortable on jumping into his house. I knew what he had made of a certain palace at Mazenderan. From being the most honest building conceivable, he soon turned it into a house of the very devil, where you could not utter a word but it was overheard or repeated by an echo. With his trap-doors the monster was responsible for endless tragedies of all kinds.