I think I hit a loophole. I got to level 15 and died at the same time, it seems. The game over screen showed up, and even a replay button, but just the game over screen stayed.
I like it alot, but sometimes it wouldn't respond. More scope time is a must, though, and I don't like the idea of scope time to begin with. Just make the money go down faster.
One of the best games I've ever played. Very hard, especially losing upgrades, but I kept playing just to see the ultimate weapons.
Rockets/bombs are the best!
I love the spacebar-for-bazooka option. This is a good, honest, fun game. I also liked the music.
As far as colour goes, maybe keep the asteroids red, or the base and planet red, or even all three, but you should change the sky colour, maybe have a day/night thing every minute or so to show passing of time.