At the main menu press 'M', 'S' and 'V' keys at the same time. This will bring up the code entering dialog. You may enter following codes:

Code Result
console - Allows "~" to Bring Up Console
god - God Mode for All Units
notgod - Disable God Mode
gimme maps - Play All Campaign Missions in "Custome Game" Menu
flashlight - Flashlight GUI Mode
from massive with love - Funny Textures
the new generation of rts-games - Play Secret Sabotage Mission in "Custom Game" Menu