Really cool concept! I played on my iPhone in the browser to get the optimal experience. I enjoyed the gameplay a lot, I was able to just tap to reload, which I thought felt pretty good. I like the sound and music, they fit the game pretty well. I was focused towards the bottom of the screen so I didn't get to read all the things up top but from what I did it was a nice addition to go along with the gameplay.
If you want to pursue this and publish to the mobile stores, I would try tapping to shoot as well instead of the dragging. It would give a little faster play with some better accuracy, but that's just my opinion.
I enjoyed the game and played a few times to get on the leaderboard - 429 at the time of writing. Great job!