music? Great. Visuals? Wonderful? Gameplay? Swinging my friend around like a hacksaw out of 10.
I seriously enjoyed this. Some more variation in enemy variety and a difficulty curve (more difficult enemies the fewer asteroids are left) would really finish it off. Also: you might not want to use the word "colonize". It's got a lot of implications that just don't fit into a cute little jam game like this. "Discover" works just as well and doesn't have those same implications :)!