There is obviously going to be some intelligent species in this game, so they will likely have a mothership to travel in space and take over planets, so why not make them attack you (and harvest your organs). But the thing is you don't fight it with your character, you fight it in your SHIP. You would take control of your ship defence systems and stop the alien invaders. Of course if there are any NPC's that fight for you they will help you in little combat ships. Also the mothership would appear randomly (after you've reached a certain point in the game of course) similar to the Goblin Invasion in Terraria. Your thoughts?