The Biodroid Empire has launched a mass attack on Earth. Fortunately, its entire network of ships use shields powered remotely from a single generator located on their homeworld. As a feared pilot, you must fly your Astrohunter spaceship through hostile territory to destroy it.

The journey is viewed from above. The threat is from nine increasingly-tough Supercruisers, which have the ability to launch spaceships, missiles and mines. These must all be avoided or shot out. In this part of the game, you have four lives, represented by shields which deplete as you take hits.

The last Supercruiser contains the six all-important Generator panels. This final phase of the game takes place on foot, as you destroy them with projectiles. You must then return to your ship before everything explodes and takes you with it.