Hybris

Hybris cheat codes: 
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.