To become indestructable, gain infinite money and fuel, complete the first attack level. When the shields/weapons screen appears, move the cursor to the top left corner of the screen. This will place it in the shields box. Now press 'FIRE' while hitting '+' on the keypad. The screen will flash, indicating that the cheat mode has been activated. If the screen does not flash, keep pressing 'FIRE' and hitting '+' simulataneously. It will work eventually. Now transfer all the energy to the weapons. Shields can still be drained by hits and colliding with objects, but once it reaches 000, the ship can not be destroyed.
The following keys will now be available during play:
'F6'-----------Replenish life meter
'F1'----Finish shoot'em up sections
'2'-'9'--------------Select weapons
'0'------------------Another weapon
'-'------------------Another weapon
'='------------------Another weapon
'1'-------------Remove extra weapon
To win at the game, simply choose the last planet as the destination. Once you enter the spaceport, there will be a short animation showing your ship leaving the galaxy.