Tunneling monster
A Tunneling monster is a monster with the ability to bore tunnels through the normally solid dungeon. Tunneling monsters can tunnel through rock and closed doors, and chop down trees.
Some monsters can only tunnel through rock while wielding a pick-axe or dwarvish mattock, and through trees while wielding an axe or battle-axe. Both picks and axes suffice for doors. Note that in your natural (not polymorphed) form you fall into this category, though the game handles the players digging differently.
Note that ANY monster that can tunnel at all can go through both rock and wood. Rock moles can eat trees and woodchucks can apparently chuck rock.
No monster can tunnel through the specially designated undiggable walls in some special levels.
Wall - When a monster tunnels through a rock wall, there is a 1/5 chance of seeing the message "You hear crashing rock."[1]
Solid rock - When a monster tunnels through solid rock (the blank areas surrounding most of the dungeon) there is a 1/3 chance of some waste being produced. 1/4 of the time this waste will be a boulder, the rest of the time it will be a single rock. No message is produced.[2][3]
Tree - When a monster tunnels through a tree, there is a 1/3 chance of a random piece of fruit being produced, chosen from amoung: apple, orange, pear, banana, eucalyptus leaf. No message is produced.[4]
Door - When a monster tunnels through a closed door there is a 1/3 chance of seeing the message "You feel an unexpected draft."[5]
Contents
Monsters capable of tunneling
Without a pick/axe
- r rock mole
- r woodchuck
- U umber hulk
With a pick/axe
- Dwarves:
- h dwarf
- h dwarf lord
- h dwarf king
- Archeologist related:
Messages
- Produced 1/3 of the time when a monster tunnels through a door.
Technical details
Monsters that can tunnel have the M1_TUNNEL monster attribute. Monsters that require picks and axes have the M1_NEEDPICK monster attribute in addition to M1_TUNNEL. No monster in vanilla NetHack has M1_NEEDPICK but NOT M1_TUNNEL.
See also
m_move in monmove.c -- decides when and if monsters can and will tunnel. mdig_tunnel in dig.c -- performs the tunneling.
