very nice game. it feels good to play and feels like a finished game.
i got to 231 . i dont know if there is more difficulty scaling after that but it feels the same from 21 kills to 200+. i repeated the same pattern for most of the game so maybe you could have made the ai a little bit less abusable.
still this is great and with a few changes could have been a solid time killer during the golden age of flash games .
good job