Cheat Codes:
During gameplay press ~ to get the console then put
in a code below.

Code Result
give all - Get all items
give life - Get Life
pause - Pauses game
toggle g_p_god - Invincibility
give jetpack- Get jetpack
give ammo - Get ammo
Give forcefield - Get forcefield
toggle r_stats - ?
camera player - ?
kill - ?
toggle r_timings - ?
toggle g_map_info - ?
toggle g_debug - ?
camera camera - ?

Cheat Method:
Press ~ to bring up the console then type in
exec cheats.cfg and press ENTER to activate cheats

Now press a letter below

G - Get Everything
H - Max Ammo
J - Get Jetpack
F - Get Forcefield
L - 1 Extra Life
K - Self-Destruct
I - Invinicibility
P - Pause