The more these 'space monsters' become unlike ships, though, the more difficult it is to deal with them in the way you'd expect to deal with them. How do you go into combat against an "energy cloud"? What will represent it on the combat grid? The fighters as a swarm of smaller creatures is doable, I guess. But beyond that you're really talking about a different type of random event than a space monster. Not that these wouldn't be useful or interesting to add to the game. Something like the "Black Cloud" that settles into your system and changes the climate/value of various planets for example.