To enter these codes, bring up the options menu (press Escape during a mission) and type the cheat code you want and click on BACK. Your radio window will tell you if you entered the code correctly.
NOTE: These codes must be typed as you see them, first letter capitalized and the rest in lowercase.

Succumb -- lose the scenario
Triumph -- win the scenario
Omnisicient -- toggle between your view and omniscient view of all troops
Pyromancer -- toggle right button explosion
Aeroballistics -- add full air support
Invulnerable -- makes sarge invulnerable
Paralysis -- pins foes in place
Telekinetic -- teleport sarge anywhere in the world (get into scroll mode first and scroll where you want to go)
Plethora -- full up on ammo
Occultation -- stealth mode (sarge won't be spotted unless he shoots)
Kahuna -- Add explosions, omniscient view, and invulnerability

Scenario Select:
At the opening menu, press A to open the first mission of each scenario.