Load the game as usual and don't do anything until the high score screen appears. Type 'COMMANDER' and then press the fire button. After a few moments press F10. If your ship flickers you are now invulnerable, and have infinite expansions and smart bombs. F1-F5 = Other Six Levels of 'expansion' (you can still capture = the capsules) F8 = Advance a level (There are three) F10 = Turn cheat mode on/off You cannot get a high score with the cheat mode on.