Clear the game on the hardest difficulty. This mode has no checkpoints, saves, icons nor reticules.
Black And White Mode
Clear Easy difficulty to unlock the "Old Movie" cheat. This basically allows the game to be played in black and white.
Infinite Ammo
Clear the game on normal difficulty to unlock infinite ammo. This cheat needs to be "reactivated" at the start of each level, if the player is killed, or he retries.
Speed This The Heck Up
Simply beat the game once on Easy. Then go to chapter select and play the very last level on a different difficulty level this will award you with that cheat.
Super Squad
Play and complete the game on Authentic Mode to unlock the super squad cheat.