I want an invasion system similar to terraria, where specific techs with unique parts only obtainable during invasions. Sky pirates may have specialized drone and plane AI's, Martians(why wouldn't they just invade earth) Could have Extreme downward beams, and Some guys that appear every 5 days at the temples to do a worship-y thingy, other things like that. Perhaps there could be a terminal for special blocks that you can buy these from(very expensive), and they have to be discovered manually before you can craft/buy them(very expensive recipe)