Cheat mode:
Go to the skirmish level selection menu. Hold [Left Ctrl] + [Right Alt] +
[Page Up] for about one second. Go back to the main menu, and then go to
"Arm Center". You should have every part and weapon available. Note: This
also unlocks every level and round in skirmish mode.
Big heads:
Press [Enter] during game play, type give me a big head, then press
[Enter] again. To return to normal size, press [Enter] during game play,
type get my head back, then press [Enter] again.