Have All Keys
Infinite Jet Pack
Infinite Pipe Bomb Ammo
Infinite Plasma Ammo
Infinite SMG Ammo
Infinite Shrinker Ammo
These are the cheats for the PAL (European/Australian) version of Duke Nukem 64.
To access the cheat menu, you have to be on the main menu, then press. ( These are done on the control pad, not the control stick ) Cheat menu: Left, down, L, L, up, right, left, up. To access the cheats you still have to be on the main menu. Invincibilty: R, C-right, R, L, R, R, R, left. No monsters: L, C-up, left, L, C-down, right, left, right. All items (including weapons and ammo): R, C-right, down, L, C-up, left, C-right, left. Level select: R, L, R, C-down, right, up, left, C-up. To level skip, when you've got the level that you want on the screen, press start.
This is really more of a glitch than it is a code. To make Duke dance, shoot one of the Dukes with Expander and then pause the game before he explodes. Access the cheat menu and turn the invincibility option on. Return to your game. Access the cheat menu again and turn invincibility off. Now Duke's "death" animation will repeat over and over. This makes it look as though the Dukester is dancing.
You need to enter the Cheat Menu Code first (see below). Then hit L, L ,L , C-Right, right, left, left, C-Left
Living Dead Duke
Take a plasma cannon, and charge it up completely. Fire it at your teammate (you must be on Cooperative). While the screen is WHITE (not RED, or it's too late) press pause, and turn on invincibility, and Duke should be completely black. Now, if you want to be either a floating dead body or a "dying Duke" (yuck: he's vomiting blood and bouncing up and down), turn on the invicibility while the screen is RED.
Switch monsters off
Go to the cheat menu (to get the cheat menu it self do this code on the main menu: LEFT, LEFT, L, L, RIGHT, RIGHT, LEFT, LEFT. Now you can get in the cheat menu.) Then hit these buttons in this order: L, LEFT C, LEFT, R, RIGHT C, RIGHT, LEFT, LEFT, RIGHT. You will here a siren if you did the code correctly. Then go in the cheat menu and now you can turn the monsters on and off.
There is a way to play big or small in Duke Nukem. This code will work on co-op or deathmatch. To do this code in co-op you need Invincibility and items codes. Turn on friendly fire, then use the weapons code, shoot your buddy with the shrinker, or expander. Small Duke: Shoot, put on invincibility then turn it off again. The player will not grow back (the drawback: you can't have any weapons). Big Duke: Get the expander, (with God mode off) and shoot the other Duke until he starts to expand. Just before he explodes put on God mode, stop shooting, then turn off god mode. You now have a giant duke that still can be killed. (Note, you may have to try it a few times to get it right).
To get the invincibility code players must first enter the cheat menu code ( Press the following at the main menu to access the hidden cheat menu: LEFT, LEFT, L, L, RIGHT, RIGHT, LEFT, LEFT. Now the cheat menu will be accessible). Then simply hit R button seven times in a row and then press left on the directional pad. A sound should signify that it worked. Now go into the cheat menu and turn invincibility on.
Duke Nukem 64 Cheat Menu
Press the following at the main menu to access the hidden cheat menu: LEFT, LEFT, L, L, RIGHT, RIGHT, LEFT, LEFT. Now the cheat menu will be accessible.
Turn Items On
Perform the code to access the cheat menu (from main menu: LEFT, LEFT, L, L, RIGHT, RIGHT, LEFT, LEFT).
Now at the main menu input: R, Right C, RIGHT, L, Left C, LEFT, Right C, RIGHT. This will enable all items to be toggled on or off.