Spend the indicated amount of Intel points at the 'Special Features' menu to acquire the corresponding cheat. To activate them, pause game play, then select the 'Enter Cheat Code' selection at the options menu. The name of the code will appear to confirm correct entry. Repeat the code to disable its effect.

Ghost Mode: Press Up(2), Left, Right, Down(2)
Increased Force (650 Intel Points): Press Right(3), Down(3)
Unlimited Ammo (550 Intel Points): Press Up, Down, Up, Down, Left, Right
Fast Movement: Press Left(3), Right(3)
Unlimited Items (550 Intel Points): Press Left, Right, Left, Right, Up, Down
Invisible (900 Intel Points): Press Down(3), Up(3)
One Shot Kills (600 Intel Points): Press Up(3), Left(3)