Debug mode:
Press C-Up, Up, C-Left, Right, C-Down, Down, C-Right, R, A, B when "Press Start" appears at the opening screen. A sound will confirm correct code entry. Use controller two to select the debug options. Press Start to cycle through the options, such as "Cheats", "Level Select", and more.

When you enter the code on the title screen and hear the horse, the Cheats Menu will be available but will have no cheats active (unless you 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. Pressing Start cycles 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 *

Multi-player debug mode:
Enable the "Debug mode" code as usual, then start a two or three player multi-player match. You can use the unused controller to control the debug menu. The best use for this is to use the warp to play the regular game with multiple players. You can complete the game as normal or fight each other. When you die, you will just reappear because you are in a Dukematch.

First person view:
Press Down, Up, L, B, Z, Left, C-Up, C-Right, C-Left, Z when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

All weapons:
Press Down, A, Up, L, Z, R, C-Up, C-Down, B, C-Left

Freeze Thrower and unlimited ammunition:
Press Down, Up, A, L, R, Z when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Rifle and unlimited ammunition:
Press C-Up, C-Down, C-Left, C-Right, L, R when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Multi-player character set 1:
Press A, L, R, Left, B, Down, Up when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Multi-player character set 2:
Press B, A(2), R, L when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Multi-player character set 3:
Press L(2), Up, Down, R, B, A when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Multi-player character set 4:
Press B(3), R, Left, A when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Multi-player character set 5:
Press Right, B, Left, L, A, Z when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

Multi-player characters set 6:
Press Up, Down, B, A(2), Left when "Press Start" appears at the opening screen. A sound will confirm correct code entry.

High speed zombies:
Press A(2), Z, A, R, C-Down, B when "Press Start" appears at the opening screen. A sound will confirm correct code entry. Alternately, rescue all babes in level 8, "Dry Town", to unlock the cheat option for high speed zombies.

Skin select:
Press C-Left, R, Left, Up, Down, B, A, Z when "Press Start" appears at the opening screen. A sound will confirm correct code entry. Go to multi-player mode and select a character. Press Start, select "Quit Game" then choose "Yes". Start a one player game to play as the person that was previously selected.

Action Nuk'em mode:
Press Down(2), A, Z(2), Left, A when "Press Start" appears at the opening screen. A sound will confirm correct code entry. Alternately, successfully complete the game. This mode allows Duke to kill opponents with one shot.

Big head mode:
Press B, Up, Down(2), A, Z, A, Right when "Press Start" appears at the opening screen. A sound will confirm correct code entry. Alternately, rescue all babes in level 2, "Liberty Or Death", to unlock the cheat option for big head mode.

Big gun mode:
Press C-Up, C-Left, Z, B, L, Z, A when "Press Start" appears at the opening screen. A sound will confirm correct code entry. Alternately, kill all opponents in level 3, "Nuclear Winter", to unlock the cheat option for big gun mode.