Complete the game for certain times to unlock following Cheats.

Unlockable	How to unlock
Decapitation	Complete Game Once.
Drug Effect	Complete Game For 8th Time.
Exploding Enemies	Complete Game For 10th Time.
Extreme Gore	Complete Game For 7th Time.
Infinite Ammo	Complete Game For 5th Time.
Infinite Grenades	Complete Game For 2nd Time.
Molotovs	Complete Game For 4th Time.
No Reloads	Complete Game For 3rd Time.
Super Shotgun	Complete Game For 9th Time.
Walking Enemies	Complete Game For 6th Time.