Dead Moon

The story begins with a comet discovered in the vicinity of Pluto that is headed on a sudden collision course with Earth. Mankind narrowly succeeds in diverting the comet's course, and it crashes into the moon. However, investigations into the damage uncover that what hit the moon was not a comet, but a gigantic mother ship. Power up your ship, destroy enemies and fight your way through the bosses in an attempt to reach the moon's core and protect Earth from alien invasion.