Offence (Frank Otto, 1994)

Enter the following cheats on the title screen:

"CHEAT ON"   = Invincibility (type "OFF" to disable)
"UNLIMITED"  = Infinite lives (type "LIMITED" to disable)

Note: Cheats only work with the full version. A sound confirms 
successful entry.

Tip: Dodge bullets by flying in circles, then fly under the long 
rock and keep pressing right - this way you won't get hit!