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.
Regain health
When you shoot a fire hydrant in the game stand next to it and press the A button.This will replenish your health to 100.
Titanic Level
To access the Titanic level "GOING DOWN" find all the time machine pieces before you get to "THE RACK" and a second exit portal should appear in the room just off the first.
Wetworld Level
To access the "WETWORLD" level play through level 3 'NUCLEAR WINTER' and when you reach the rail tracks leading to the communicator you have to power up drop off onto the roof below where you will see a medi kit. Now jump off this roof into the water (which is only on 1 side) and swim to a floating platform where you will see the level exit.
Unlock All Cheat Options
At the Press Start screen, press C-Left, Left, Up, C-Right, R, R, C-Down, L, C-Up, Up, Right, C-Right, Start.
First Person View
At the Press Start screen, press Down, Up, L, B, Z, Left, C-Up, C-Right, C-Left, Z.
.30-.30 Rifle with Infinite Ammo
At the Press Start screen, press C-Up, C-Down, C-Left, C-Right, L, R.
All Guns with Infinite Ammo
At the Main Menu, press A, B, A, C-Up, C-Down, Left, A.