At the main menu, select "Options", then choose the "Cheats" selection. Then, enter one of the following codes to activate the corresponding cheat function:

-Infinite Feral Attacks
  Enter "Bloodlust" as a case-sensitive code.

-Infinite ammunition
  Enter "UnleashHell" as a case-sensitive code.

-Restore health
  Enter "ImJackCarver" as a case-sensitive code.

-Feral Attack in the early levels
  Enter "FeralAttack" as a case-sensitive code.

-All maps
  Enter "GiveMeTheMaps" as a case-sensitive code to unlock all maps.

Note: This code cannot be disabled unless your profile is deleted.