Debug mode
When "Press Start" appears at the opening screen, press C-Up, Up, C-Left, Right, C-Down, Down, C-Right, R, A, B. If you entered the code correctly, you will hear a sound. The "Cheats Menu" will be available but will have no cheats active (unless they were previously activated or earned). Once you start or load a game/level, text will appear in the upper/left hand corner of the screen. Use controller two to control the debug options. Press Start to cycle through the various lists of options. Use the buttons noted below to change certain values. Note: Debug mode does not save on the memory pak like the other cheats.

SFX

L or R: FX down/up
Left or Right: FX down/up by 10
B: First person view
A: Third person view
Z: Play SFX
Level Warp

L or R: Level down/up
B: Skip level
Z: Advance to selected level
Midi

L or R: Song down/up
A: Play song
B: Stop song
Global Palette
B or A: Red down/up
C-Left or C-Down: Green down/up
C-Up or C-Right: Blue down/up
Cheat

Z: All weapons
L: All items
R: All keys
A: Invincibility
AI Debug Values
B or A: GVAR 1 down/up
C-Left or C-Down: GVAR 2 down/up
C-Up or C-Right: GVAR 3 down/up
Fog*

B or A: Red down/up
C-Left or C-Down: Green down/up
C-Up or C-Right: Blue down/up
Left or Right: NR down/up
L or R: FR down/up
Sky Top*

B or A: Red down/up
C-Left or C-Down: Green down/up
C-Up or C-Right: Blue down/up
Sky Bottom*

B or A: Red down/up
C-Left or C-Down: Green down/up
C-Up or C-Right: Blue down/up
Clouds 1*

B or A: Red down/up
C-Left or C-Down: Green down/up
C-Up or C-Right: Blue down/up
L or R: HT down/up
Down or Up: AN down/up
Left or Right: SP down/up
Clouds 2*

B or A: Red down/up
C-Left or C-Down: Green down/up
C-Up or C-Right: Blue down/up
L or R: HT down/up
Down or Up: AN down/up
Left or Right: SP down/up
Player

L or R: DN Down/Up (changes player's character)
GFX

(Values cannot be changed)
AI

A: AI 0/1 (set to 1 to stop enemies)
L: Difficulty 0/1/2
R: Auto aim 0/1
Alpha Palette

B or A: R0 down/up
C-Left or C-Down: G0 down/up
C-Up or C-Right: B0 down/up
L or R: R1 down/up
Left or Right: G1 down/up
Down or Up: B1 down/up
Weather Cheat works the same way but only has the options noted with an *

All weapons
When "Press Start" appears at the opening screen, press Down, A, Up, L, Z, R, C-Up, C-Down, B, C-Left. If you entered the code correctly, you will hear a sound.

Rifle with infinite ammunition
When "Press Start" appears at the opening screen, press C-Up, C-Down, C-Left, C-Right, L, R. If you entered the code correctly, you will hear a sound.

Freeze Thrower with infinite ammunition
When "Press Start" appears at the opening screen, press Down, Up, A, L, R, Z. If you entered the code correctly, you will hear a sound.

Group 1 multi-player characters
When "Press Start" appears at the opening screen, press A, L, R, Left, B, Down, Up to unlock all Group 1 multi-player characters. If you entered the code correctly, you will hear a sound.

Group 2 multi-player characters
When "Press Start" appears at the opening screen, press B, A(2), R, L to unlock all Group 2 multi-player characters. If you entered the code correctly, you will hear a sound.
Group 3 multi-player characters
When "Press Start" appears at the opening screen, press L(2), Up, Down, R, B, A to unlock all Group 3 multi-player characters. If you entered the code correctly, you will hear a sound.

Group 4 multi-player characters
When "Press Start" appears at the opening screen, press B(3), R, Left, A to unlock all Group 4 multi-player characters. If you entered the code correctly, you will hear a sound.

Group 5 multi-player characters
When "Press Start" appears at the opening screen, press Right, B, Left, L, A, Z to unlock all Group 5 multi-player characters. If you entered the code correctly, you will hear a sound.

Group 6 multi-player characters
When "Press Start" appears at the opening screen, press Up, Down, B, A(2), Left to unlock all Group 6 multi-player characters. If you entered the code correctly, you will hear a sound.
Skin select
When "Press Start" appears at the opening screen, press C-Left, R, Left, Up, Down, B, A, Z. If you entered the code correctly, you will hear a sound. Skins may be selected in single player mode, but may not be viewed during selection.

First person view
When "Press Start" appears at the opening screen, press Down, Up, L, B, Z, Left, C-Up, C-Right, C-Left, Z. If you entered the code correctly, you will hear a sound.

Action Nuk'em mode
When "Press Start" appears at the opening screen, press Down(2), A, Z(2), Left, A. If you entered the code correctly, you will hear a sound. Alternatively, successfully complete the game to unlock Action Nuk'em mode, which allows Duke to kill opponents with one shot.

High speed zombies
When "Press Start" appears at the opening screen, press A(2), Z, A, R, C-Down, B. If you entered the code correctly, you will hear a sound. Alternately, rescue all babes in level 8, "Dry Town", to unlock the cheat option for high speed zombies.

Big head mode
When "Press Start" appears at the opening screen, press B, Up, Down(2), A, Z, A, Right. If you entered the code correctly, you will hear a sound. Alternately, rescue all babes in level 2, "Liberty Or Death", to unlock the cheat option for big head mode.

Big gun mode
When "Press Start" appears at the opening screen, press C-Up, C-Left, Z, B, L, Z, A. If you entered the code correctly, you will hear a sound. Alternately, kill all opponents in level 3, "Nuclear Winter", to unlock the cheat option for big gun mode. -

Flat shade map
When "Press Start" appears at the opening screen, press Down, Up, Left(2), A, Right, Down. If you entered the code correctly, you will hear a sound. Alternately, obtain all secrets in the "Wetworld" secret level to unlock the cheat option for flat shade map.

Ice skin
When "Press Start" appears at the opening screen, press B, Z, Up, L, A, C-Right, A. If you entered the code correctly, you will hear a sound. Alternately, rescue all babes in level 5, "Fallout", to unlock the cheat option for ice skin.

Weather
When "Press Start" appears at the opening screen, press Z, A, L, B, Down, Up, R. If you entered the code correctly, you will hear a sound. Alternately, obtain all secrets in level 6, "Under Siege", to unlock the cheat option for weather.
Extreme mode
Successfully complete the game with all babes rescued and all opponents killed to unlock Extreme mode, which allows the game to be played at a higher difficulty setting.

Bonus multi-player characters
Successfully complete any level and save the game to unlock one additional character in multi-player mode.

Maximum blaster ammunition
Kill all opponents in level 9, "Jailbreak", to unlock the cheat option for maximum blaster ammunition.

Maximum shotgun ammunition
Rescue all babes in level 10, "Up Ship Creek", to unlock the cheat option for maximum shotgun ammunition.

Maximum rifle ammunition
Rescue all babes in level 11, "Ft. Roswell", to unlock the cheat option for maximum rifle ammunition.

Maximum revolver ammunition
Kill all opponents in level 12, "Probing The Depths", to unlock the cheat option for maximum revolver ammunition.

Maximum sawn-off shotgun ammunition
Kill all opponents in level 13, "Whitechapel Killings", to unlock the cheat option for maximum sawn-off shotgun ammunition.

Maximum SMG ammunition
Obtain all secrets in level 15, "Dawn Of The Duke", to unlock the cheat option for maximum SMG ammunition.

Maximum gatling gun ammunition
Kill all opponents in level 16, "Hydrogen Bomb", to unlock the cheat option for maximum Gatling gun ammunition.

Maximum Volt C. ammunition
Obtain all secrets in level 17, "The Rack", to unlock the cheat option for maximum Volt C. ammunition.

Maximum sniper ammunition
Rescue all babes in the "Going Down" secret level to unlock the cheat option for maximum sniper ammunition.

Maximum freezer ammunition
Kill all opponents in level 20, "The Brothers Nukem", to unlock the cheat option for maximum freezer ammunition.

Maximum gamma ammunition
Rescue all babes in level 21, "Alien Mothership", to unlock the cheat option for maximum gamma ammunition.

Wetworld level
Play through the "Nuclear Winter" level until reaching the rail tracks leading to the communicator. Then, power up and drop off onto the roof below where a medi-kit can be seen. Jump off this roof into the water (which is only on one side). Swim to a floating platform, where the level exit will appear.

Going Down level
Collect all the time machine pieces before reaching "The Rack" level. Then a second exit portal will appear in the room just off where the first is located. Use it to reach the "Going Down" (Titanic) level.

Refill health
Destroy a fire hydrant or another water source. Then, stand in the water and hold A to slowly restore health. Alternatively, stand in front of a toilet or urinal and press A.