During the gameplay press T to bring up the console then enter any of these codes:
/godmode: God Mode
/nextlevel: Next Level
/room #: Teleport to Room #
/spawn #: Spawn Object #
/moregold: Add 100 Gold
/tinymonsters: Tiny Monsters
/tinyplayers: Tiny Players
/insanity: Monsters attack each other
/repeat: Repeat last cheat