Unlock the following cheats in Single-Player mode by completing the corresponding tasks:

CHEAT - HOW TO UNLOCK
Fiery Death(enemies disintegrate) -  Earn the "Secret Master"achievement by finding all secrets in all single player missions. Whenthis cheat is activated, enemies die as if they were killed by acharged shot.
Fully Stocked(infinite ammo) - Earn the "Annihilator Award" achievement by killing 1,000 enemies.
Stopping Power(one-shot kills) - Earn the "Campaign Award" achievement by completing all single player missions.