Move, shoot, move shoot, yawn, quit.
OK, you've got an interesting start. But the problem is you just don't take it far enough. The graphics aren't at all bad, but I've seen better. You're above average. Your sound quality is fine - no hisses or pops but the only sounds there are here are gunshots, groans, and splats. Play this game for 2 minutes and you'll hear just about every sound effect there is in it. Not good. The whole move, shoot, repeat machanic is acceptable considering this is a one-person project but there are other games in this genre which mix things up a bit.
The biggest issue I have is simply the lack of incentive to keep playing. One person before me said once you get to the good weapons you can't lose. Well another problem is getting to any kind of good weapon to begin with! After 3 rounds of being stuck with the standard pistol I just saw no reason to keep playing. The time it would take to build enough EXP to acquire a better gun I decided would be better spent just quiting and playing another game instead. You have to work out a balance with rewarding the player - keep some waiting too long and they'll quit because they're not getting anything out of it. Give them something that's too powerful and the game becomes too easy. It's a balancing act that can be difficult to master but keep at it. You've got potential.