Star Sentry

Publisher's blurb The Place: a remote outpost on an ice world light years from earth. Suddenly the small planet Thule is surrounded by alien life orbs destined to change the atmosphere to suit themselves. However, this spells certain death for your base as the frozen mountains start to melt. You take command of your single seat fighter to destroy the aliens before it's too late. But you didn't know the aliens had help... Star Sentry is an arcade-type space action game written entirely in machine language for one player.