Press ~ to enter the console. Now type in the following codes:

iwillsurvive 			- God Mode 
takeittothelimit 		- Ammo Reload     
hitmewithyourbestshot 	- Expert CPU
raindropskeepfallinonmyhead - Allows call for Artilley Shells. Re-enter for more.
closetoyou 			    - Invisibility
gamma#                  -set gamma to #
turbo                   -run faster
sky                     -sky details (see for yourself)
letmego                 -level select

Thanks to Revolution readers Mr. Hapkido 2u, The Groz, CaInE357, Tom Bowen, MasterD, Jerry Almond, Lionel Chau, Cpt. Death, Bryan Stedman, NDOE, K.P., C.J., josh hutter and Alex Spratling!