Heretic

COCKADOODLEDOO: turns you into a chicken for a short time.
ENGAGExy: level warp: x is episode, y is level.
IDDQD: player dies: "Trying to cheat, eh? Now you die!".
IDKFA: removes all weapons: "Cheaters don't deserve weapons".
KITTY: toggles clipping on and off.
MASSACRE: kills everything on the level but player.
PONCE: grants 100% health.
QUICKEN: toggles invincibility on and off.
RAMBO: grants all weapons and ammo.
RAVMAP: use in map mode: reveals game map.
SHAZAM: toggles Tome of Power on and off.
SKEL: gives player all keys.
TICKER: prints a frames-per-second rating onscreen.
GIMMExy: get items: x is item (A-J), y is quantity (1 to 9):.
A: ring of invincibility.
B: shadowsphere (invisibility).
C: Quartz Flask (adds 25% health).
D: Quartz Flask (adds 100% health).
E: Tome of Power (doubles weapon strength).
F: Torch (light amplification).
G: Time Bomb (kablooey!).
H: Morph Ovum (turns foes into chickens).
I: Wings of Wrath (grants flying ability).
J: Chaos Device (restarts level).