There was only 20 waves? :( I played till 18 on newgrounds and stopped because round 18 was really long and boring.
If I'd know there was only 2 more stages I would have kept going...
Needs bosses.
Finished level nine and at that point you had a 4 star, and it would have gotten higher.
Exclusive content, lol 2/5. Also, make the end of level points thing quicker at the start. Very boring when the score takes longer than the game.
Got bored and was trying to kill myself before the first boss. Not sure what you could to to improve though. More weapons, more enemy's and a bigger arena would be a start.