Impressive as hell, if you showed me this without any context I would never guess it was made for a game jam. I can't think of anything I didn't like. Bullet hell is always nice, the gameplay are graphics are great and I really enjoyed the "small planets spawning" mechanic, since it adds this "should I let more spawn to get money or should I just hurry killing the boss in case I mess up?" factor.
...I really hope the infected planets aren't, you know, inhabited.