Start a new game then pause the game and press square, circle, R1, L1, R1+R2. To get this code to work you have to enter it within two seconds.
Start a new game then pause it and press square, circle, L1, L1+L2.
Run Faster in Multi-Player Mode
Hold square+triangle to chase your opponent quicker in multi-player mode.
In level two kill the blue spy and pick up the information that he leaves behind. Then when you are ordered to evacuate the area ignore those orders and go to the tan post. Kill the guys there and cycle through your weapons until you see info as your weapon. Press select and read it. Then go hunting for the artifact.
Go to the two player level "Clean Up This Mess!" and go into the closet that is located in the North East direction. You will find a key located between two books. Once you have the key look at your radar. You will then see two doors. One is the closet and the other is where you use the key you found. Take the key there. When you get close enough to it you will automatically use the key.