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.