Unlock all Missions and gallery pictures:
To unlock all Missions and Gallery pictures press the following combination at the Press Start screen:
L2, R2, L1, R1, L1, L2(2), R2, L1, R1(2), R2.

Add Weapon:
To add a weapon press the following combination at the Press Start screen and the Add Weapon option will appear when the game is paused: Up, Down, Left, Right, Circle, Square, Up, Down, Left, Right, Circle, Square.

Infinite Ammunition:
To have infinite amunition press the following combination at the Press Start Screen:
R2, R1, Triangle, L2, L1, Up, R2, R1, Triangle, L2, L1, Up.

Invincibility:
To have ivincibility press the following combination at the Press Start screen:
R3, L3, Right, Left, L1, R1, R3, L3, Right, Left, L1, R1.

Psychedelic Mode:
To play in Psychedelic mode press the following combination at the Press Start screen:
Up, R2, Circle, Left, Triangle, Square, L2, L1, Circle, R1.