Press ESC then type in these codes:

Kahuna - Add explosions, omniscient view, and invulnerability
Invulnerable - Invulnerable Sarge
Plethora - Full ammo
Occultation - Stealth mode
Aeroballistics - Full air support
Paralysis - Frozen enemies
Telekinetic - Teleport sarge - activate scroll mode first
Triumph - Win scenario
Succumb - Lose scenario
Omnisicient - Overall view toggle
Pyromancer - Right button explosion toggle