Cheat Mode:
Enter Y, X, B, X, Y, A, B, A at the cheats screen under the Options menu to unlock Cheat mode
All Cheats Unlocked:
Enter B, B, A, A, Y, X, Y, X at the cheats screen
Level Select:
Enter X, Y, A, B, Y, X, A, A at the cheats screen
Super Health (recover from non-fatal wounds more quickly):
Enter A, A, Y, B, Y, B, X at the cheats screen
Infinite Ammo:
Enter Y, B, A, X, Y, X, A, B at the cheats screen
Infinite Grenades:
Enter X, A, X, Y, A, X, A, X at the cheats screen
Bouncy Grenades:
Enter X, X, X, X, X, X, X, X at the cheats screen
Gibby Explosions:
Enter B, X, A, Y, B, X, A, Y at the cheats screen
Gibby Ammo:
Enter A, A, A, A, X, Y, A, A at the cheats screen
Rapid Rails (allows railgun shots to travel at high speed and allows rapid firing of railgun shots. This cheat works best when combined with Infinite Ammo):
Enter X, Y, X, Y, A, A, B, B at the cheats screen
Extra Chunky mode (makes enemies explode into bloody chunks when hit):
Enter X, X, X, X, B, A, X, X at the cheats screen
Walking Dead:
Enter A, A, A, A, A, A, A, A at the cheats screen
Wacky Deaths:
Enter B, B, B, B, B, B, B, B at the cheats screen
Rain of Fire:
Enter Y, Y, Y, Y, Y, Y, Y, Y at the cheats screen
Director's Cut:
Enter Y, A, X, B, X, A, Y, B at the cheats screen
Joke Message (does not always work...):
Enter Y, A, Y, A, Y, A, Y, A at the cheats screen
HINT FOR USE:
Do NOT combine Walking Dead with Extra Chunky. It can freeze the game, or cause neither cheat to work.
The best combo is: Infinite Ammo, Infinite Grenades, Super Health, Extra Chunky, Gibby Explosions, Gibby Ammo and Rapid Rails.
Be careful with the Level Select. It does NOT show up on the Cheats menu. It shows up in Single-Player mode. If you advance to a level you have not reached normally, you will only have the NanoGL and one Pistol. That's all. Even with the other cheats active, it would be VERY unwise to take on Molov (even in Easy mode) with just those two weapons...
At the cheat menu enter the following-
Joker Cheat - Y, A, Y, A, Y, A, Y, A
Unlimited Grenades Cheat - X, A, X, Y, A, X, A, X
Unlock All Cheats - Y, X, B, X, Y, A, B, A
Unlock All Options - B, B, A, A, Y, X, Y, X
Wacky Death Cheat - B, B, B, B, B, B, B, B
Walking Dead Cheat - A, A, A, A, A, A, A, A
Fat Cheat - X, X, X, X, B, A, X, X