Fly through space to a moon on a top to bottom scrolling screen, dodging and shooting while managing your fuel. Then on the moon (just colored bars obscuring the space scene) continue the scrolling picking up miners a la Defender.
From the Back of the Box:
Rescue miners stranded on moons in the four galaxies of Quadrant Jupiter2! Brave deadly meteor showers, comets, alien vessels and space debris. Sweep across the moonscape, searching for marooned miners. Reach all the miners you can carry, then head through Accelerator Rings! Blast off and make for another moon! Can Moonsweeper survive this mission of mercy?