Various cheats        

God Mode:
     At  the  title screen, press R3, L3, Right, Left, L1, R1, R3, L3,
Right, Left, L1, R1.

Unlimited Ammo:
     At  the title screen, press R2, R1, Triangle, L2, L1, Up, R2, R1,
Triangle, L2, L1, Up.

All Missions and Pictures:
     At  the  title  screen, press L2, R2, L1, R1, L1, L2, L2, R2, L1,
R1, R1, R2.

Add Weapons Option (when paused):
     At the title screen, press Up, Down, Left, Right, Circle, Square,
Up, Down, Left, Right, Circle, Square.

Acid Trip Mode:
     At  the  title  screen,  press  Up,  R2,  Circle, Left, Triangle,
Square, L2, L1, Circle, R1.