Heretic cheat codes

Instructions
To use a cheat code in most versions of Heretic, one simply types the code while playing (this also applies while in automap mode). After the last letter has been entered, a message of acknowledgement will appear at the top of the screen. The status bar and ingame view may also change, depending on the effects of the code. All of the codes for the original game work in all source ports, unless otherwise noted.

All codes are disabled in multiplayer games and in the Black Plague Possesses Thee skill level.