Press Ctrl+X to bring up the console, then type invisibility and you will turn invisible.
Contributed By: gameprsn.
Various Cheats and codes
During gameplay, press ''Ctrl+x'' and type the following(without the quotes):
''cavalry'' for invincibility
''hemmit'' to enable all weapons
''medic'' to strengthen your shields to full strength
''killjoy'' to get free hover technology
PS:Codes are case sensitive
Contributed By: EHazarika.
Secret to get a nuke and homing missles
On the last part of the first mission, you will see a little shack behind a few trees. Destroy the trees and blow the shack. A small car will come out and run around. Chase it and smash into it to get a free nuke. Remember the shack? Go back inside to find a homing missle.
Contributed By: Ryan Two.