Various cheats
     Press  escape  (ESC)  during  game play and enter your which ever
code  you  want. You won't get any confirmation that anything has been
enabled.

Cheat code:             Effect
IFUMANA	                Unlimited Mana
IFGDGUN 	        Gives you a pistol.
IFDAMAGE 	        More damage for the the weapon
IFDAURA 	        Change aura to infernal.
IFUAMMO 	        Full ammo including grenades and mines.
IFGPLASMA 	        Gives you a plasma gun.