Additional characters in multi-player mode

Complete any level and save the game to unlock an additional character in multi-player mode.

Character set 1

Press A, L, R, Left, B, Down, Up when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Character set 2

Press B, A (x2), R, L when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Character set 3

Press L (x2), Up, Down, R, B, A when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Character set 4

Press B (x3), R, Left, A when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Character set 5

Press Right, B, Left, L, A, Z when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Character set 6

Press Up, Down, B, A (x2), Left when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Freeze thrower with unlimited ammunition

Press Down, Up, A, L, R, Z when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Rifle with unlimited ammunition

Press C-Up, C-Down, C-Left, C-Right, L, R when “Press Start” appears at the opening screen. (A tone confirms correct entry.)

Secret level: Going Down

Obtain all of the time machine pieces before reaching the rack. A second portal should appear in a room adjacent to the first.

Secret level: Wetworld

After powering up at the end of level 3: Nuclear Winter, jump onto the roof below. (You will see a Medkit there.)
From the roof, jump into the water and swim to the floating platform.

Perform the following tasks to enable the respective cheats.

Big head mode
Rescue all babes on Level 2: Liberty or Death

Big gun mode
Kill all opponents on Level 3: Nuclear Winter

Flat shade map
Find all secrets on Level 4: Wetworld

Ice skin
Rescue all babes on Level 5: Fallout

Weather
Find all secrets on Level 6: Under Seige

High-speed zombies
Rescue all babes on Level 8: Dry Town

Max. blaster ammo
Kill all opponents on Level 9: Jailbreak

Max. shotgun ammo
Rescue all babes on Level 10: Up Ship Creek

Max. rifle ammo
Rescue all babes on Level 11: Fort Roswell

Max. revolver ammo
Kill all opponents on Level 12: Probing the Depths

Max. sawn-off shotgun ammo
Kill all opponents on Level 13: White Chapel Killings

Max. SMG ammo
Find all secrets on Level 15: Dawn of the Duke

Max. gatling gun ammo
Kill all opponents on Level 16: Hydrogen Bomb

Max. Volt C. ammo
Find all secrets on Level 17: The Rack

Max. sniper ammo
Rescue all babes on Level 19: Going Down

Max. freezer ammo
Kill all opponents on Level 20: The Brothers Nukem

Max. gamma ammo
Rescue all babes on Level 21: Alien Mothership

Extreme Mode:

Beat every level, rescue all of the babes and kill all of the enemies to access Extreme mode.

Action Nuk'em Mode:

Beat the game to unlock this mode, which allows one-shot kills.

First-person view:

At the opening screen, press Down, Up, L, B, Z, Left, C-Up, C-Right, C-Left, Z. You'll hear a sound to confirm.

Regain health:

Shoot a fire hydrant or toilet, stand next to it and press A. You will slowly regain health.