Duke Nukem 3D

Debug Mode from David and Attack
At the main menu hold x,y,z,l, and r for about 15 seconds until input info on appears at the bottom of the screen. During the game there will be some debugging info at the top of the screen.

All weapons from Joel Hamilton/substance J
Pause the game and press Z, X, X, Z, Y, Z, Y, X, Y.

God Mode from Joel Hamilton/substance J
Pause the game and press X, Z, Z, X, Y, X, Y, Z, Y.

Level select from Joel Hamilton/substance J
At the MAIN MENU screen press X, Y, Z, Z, Y, X, Y, Z, Y.

Turok Style Control from Lo Wang
Pause the game at at any time and press Y,Y,Z,Z,X,X,Y,X,Z for Turok style controls. Here are the controls:
A:open door/Drink/Action
B:Backward
C:straf right
X:use item
Y:straf left
Z:Walk Forward
L:Shoot
R:Jump
D-padUp/Down: Select item
D-Pad/Left/Right:Select Weapon

How to get the hidden game "DEATH TANK Zwei" from Ryle
Load one time the game with a saving of EXHUMED or QUAKE in the memory. "DEATH TANK" will appear on the main menu. If you haven't got EXHUMED or QUAKE, you can get DEATH TANK Zwei if you shoot and destroy EVERY toilet and urinals in the game (except the giant one at stage UREA 51) and finish the game. The hidden game should then appear.

No Monsters from Ryle
At the "Skill Level" screen enter Z, Z, X, X, Y, X, Y, X, Z and the new skill level "No Monsters" will appear.