Absolute Zero

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.