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Doom codes are:
IDDQD=God Mode
IDKFA=All weapons, Keys, and Ammo!
IDBEHOLD=Debug options. A menu will appear on the screen.
Type in the first letter of an option you want.
IDSPISPOPD=No Clipping(walk through walls).
IDCLEV=Warp. You type this in, then type the episode1-3 and the level you want.