As with "Doom", "Heretic" contains various cheat codes that allow the player to be invulnerable, obtain every weapon, be able to instantly kill every monster in a particular level, and several other abilities. If the player uses the "all weapons and keys" cheat ("codice_1") from "Doom", a message appears warning the player against cheating and takes away all of his weapons, leaving him with only a quarterstaff. If the player uses the "god mode" cheat ("codice_2") from "Doom", the game will display a message saying "Trying to cheat, eh? Now you die!" and kills the player character.