I like the core idea, I think it could use some iterating. I would have preferred much more free movement than being locked to a grid, and I'd love to see the game interact with the changing of scale. With how hard the game was, I didn't feel like the scale really made much of a difference; maybe if the larger you are, the more powerfully you could shoot, but doing anything besides a weak shot would use up some of your size? And maybe when you get hit, it would knock pieces off the player which would become asteroids themselves, instead of instantly losing the game.