Hurray, a critique
It's a good concept, and I was drawn into finishing the game because of it. The character art could use some improvement, but you'll improve as you work, so don't stress over that too much.
The atmosphere works, although it could be spookier. Gun selection, as other people have already commented, definitely needs some other alternative as it's incredibly difficult to switch weapons. Money might be earned a little faster for upgrades, but I didn't have any huge problems getting to the end and customizing on the budget was a decent challenge. The dream sequences after each round became dull, also. It might help to mix things up a little there, maybe include several different ones similar to the beach (which felt non-sequitir without anything else like it).
The biggest problem I have is the ending: button-mashing on a keyboard, or even at all, is a horrible mechanic. I feel like a short maze or even something rhythm-based would have worked more effectively than "mash that spacebar."
I feel that the weapons and their upgrades were nicely balanced against the enemies, even if the AI did have a tendency to shoot at the ground instead of nearby targets occasionally. So good job there, it can be difficult to get things nicely balanced.