All weapons
pause the game and press square,circle,R1,L1
Submitted by WeldingRC
All levels
at main menu, hold L1+R1+O AND PRESS UP, DOWN,LEFT,RIGHT.
Submitted by black knight
Tips/Hints
Tanks Make you die
Avoiding Tanks is key. They can be heard before seen. Listen for the engine rumbling sound and use yyour radar to determine where its comming from. Then avoid it.
You too can use the Sniper rifle
As cool as the sniper rifle is, its not very accurate. Its still very useful. It can be used in foggy areas to peer through it and locate enemy soldiers and tanks before they can see you. Also when entering hot zonesm you can crawl foward on your belly and pick off soliders. When taking out tanks, you can establish your Bazookas aim by aiming with the sniper riffle then quickly switching to the bazooka and firing and taking out a tank you can't even see.
The Doom Tactic
Remember Doom and the exploding barrels? Well if you don't, you can save ammo and take out groups of enemies by aiming at barrels