Unlimited Ammo
     During gameplay, press Select, hold R1 + Square and press Left.

God Mode
     During  gameplay,  press  Select, hold L1 + L2 + R1 + R2 + Square
and press Left.

Heavy Weapons with Full Ammo
     During gameplay, press Select, hold L2 + R2 + Square and press Left.

Melee Weapons
     During gameplay, press Select, hold L1 + R1 + Square and press Left.

No Clipping
     During  gameplay,  press  Select,  hold L1 + L2 + R1 + Square and
press Left.

No Gravity
     During  gameplay, press Select, hold L1 + L2 + R2 + Left + Square
and press Start.