Took me a while to realize that money is preserved after death. Also, the machine gun weapon seems a bit funky, I feel like it should shoot while you're holding the mouse instead of using a switch that turns it on and off. I also think more cues when you hit the enemies would make the game much better; on anything other than a one-shot it was really hard for me to tell if I was even hitting the enemies at all.
Anyway, congratulations on your first game!