I really loved the physics of it all, the black particles flying around everywhere, big black holes absorbing little ones and of course the bullets going around the black holes. I particularly love the screenshake, it gave a real sense of power as you approached the black hole. I feel like there could be some extra variety, perhaps different enemy types or maybe different weapons? Perhaps there could be some strategic way of shrinking and eventually destroying black holes to keep the game going longer and add some extra depth to clear the battlefield. Even without this depth, I played a few times in each difficulty and really enjoyed it!