After a long interstellar voyage the colonists established residence on the asteroid, in a complex named Astral. Sadly, troubles were sure to follow, in the form of raiding spaceships full of bloodthirsty monsters. You (and up to two other friends) play well-armed colonists, taking back infested colony chambers one series of furious firefights after another, running around rooms whose layouts are known but whose monstrous denizens are concealed by the fog of war. Fortunately, there are a wide array of bonuses and bounties to collect from slain monsters, to be used and spent in the store between levels, changing tactics courtesy of an assortment of firearms and explosive devices.