Invincibility
Start a mission, pause the game and press Square, Circle, L1, L1 + L2. This code must be re-entered on each level.
Submitted by JUAN CARLOS LOPEZ
Level Select
At the Main Menu, press Square, Circle, R1, L1, R1+L1.
Submitted by JUAN CARLOS LOPEZ
Run faster in Multiplayer:
Hold Square + Triangle to chase your opponent more quickly.
Submitted by JUAN CARLOS LOPEZ
All Weapons,
After you have started the mission, press the start button to bring up the pause screen. These codes must be put in within 2 seconds then press square,circle,R1,R2,then R1+R2.
Infinite ammo
square circle L1 L1+L2
Submitted by kokocat
Tips/Hints
Slowly but surely
Walk slowly whenever possible. You can often spot enemy soldiers outside his cone of vision and take him out sniper style with one quick shot
Grenades Aiming skils
To get a higher chance of a kill, toss grenades slightly short since they have nasty habit of bouncing/rolling past your target.