I did not had a lot of time to try it, but I liked what I saw, apart from the buying bullet system I think if we could buy some ammo inside a level, that would really help.
Also I did not tried, but what if you spent all your money and ammo without completing the first level? Are you stuck then?
thanks for the feedback, I added free bullets & TNT & Few coins to start with, Don't forget that there is a free bullets every 2 minutes of playing, so the player can never be stuck!