At the main console (hit Backspace), type in:

ALLCAPS All weapons, items, ammo
AMMO full ammo
ARMOR 200 % armor
CHOJIN become immortal
FREEZE (debug) freeze all monsters.
FULLMAP view the full map
INVISIBLE 2 minutes of invisibility
KEYS all keys
KILL kill every thing immediately
REANIMATE (debug) reanimate all monsters.