Load the game and wait until the high score screen
appears. Type commander and press Fire. Wait approximately
two seconds and press [F10] to enable cheat mode. Your
ship will flicker to confirm correct code entry. During cheat
mode, your ship will be invincible, and have unlimited expansions
and smart bombs. Additionally, one of the following keys may
be pressed to activate the corresponding cheat function. Note:
High score will not be recorded while cheat mode is enabled.

Key
Other six levels of expansion [F1] - [F5]
Level skip [F8]
Toggle cheat mode [F10]