Select Cheats Menu from the Options menu and enter GiveMeTheMaps.
Passwords
From the main menu, go into "Options" and select "Cheats". Enter the following:
Password - Effect
FeralAttack - Feral attacks in early levels
ImJackCarver - Refills health
UnleashHell - Unlimited ammo
Bloodlust - Unlimited feral attacks
GiveMeTheMaps - Unlocks all maps