Close to a perfect 10.
That missile moves just a little too fast once you get to orbit, it just speeds away.
Everything else was great. The music was a perfect choice for this. The graphics are good, but not so detailed that the game is over 3MB, nor laggy. The gameplay was smooth, although I would have liked to see keys for melee and the boost. Also, it would have been nice to separate the Rocket fire button, and the laser attack, I often found myself wishing I could unleash the rockets at a different time depending on the amount of opponents I had.
Really, a great game with good replayability, although I didn't notice the ability to upgrade until after my first run through.
I hope you had fun making this game, because I had fun playing it, and I'm sure tons of other people will too.