In the 24th century, on the frozen Jovian moon of Europa, Earth has established a colony to extract water from the moon. One of the mining facilities accidentally discovers on their excavations members of a long-buried alien race. The creatures, now awake, slaughter all the miners and destroy the moon's capital city. It's up to you now to defend what's left of the colony and eliminate the aliens, or at least hold them off until help arrives.
Gameplay consists of 3D space combat action (though mostly on the moon's surface) with a twist: you don't play a specific character or campaign. Instead, you are placed in the shoes of different characters with each new mission, each of them trying their best to survive using 7 different vehicles, from starfighters, to recon scouts, to ground-based turrets.