Well how did this happen? One minute you're playing with your buddies and the next you're teleported to a distant moon and exploring the remains of what appears to be an alien facility.
The aliens are intelligent. Well, some of them are. But regardless they all hold vital information as to the events that plunged the lost moon base into chaos.
The more of them that you zap the more information can be beamed back to star command.
Good luck!