Interesting concept, but I'd say it's a bit of a bad execution. First of all, you should really show the ammo somewhere, there's no reason to hide it. Secondly, there are a few weird bugs with the finish, which you can move around for some reason and you can play the sound multiple times. The sounds are really nice, though they're a bit too loud imo. It's interesting that you can move the spikes around with your bullets, but they do give off an amateur feel, and besides, I don't think that was the main gimmick of your game anyway.