Hmm...
That wasn't so original. There were several things I disliked as well. First off: by the end of the second chapter, you have buyed the ultimate weapon and most of the rest of the equipment, so collecting money is no longer fun. Secondly, what about the psycho and the cop? 10 achievements using the gentleman for what? I restarted the game with the psycho just to find out he was as weak as the previous character I used (though the game is really easy). I can't really praise you on the graphics, but they were to be expected for THAT kind of game. It was a nice, fun game, but I don't think the third chapter was needed. You could have ended it in the second chapter, or put a nice "story mode" to make it more interesting throughout all levels. That's all.