I played it to the end. Nothing too exciting though, that's just my opinion.
I think the blobs that the enemy skeletons shoot travel a bit too fast. Sometimes there was no avoiding being hit as you hid enemies just around the corner. The element of surprise was intended, but I didn't 'stand a chance' of avoiding being shot so it felt a bit unfair.
Also the health bar.. couldn't figure out how much health I had left, I think a simple health bar or plain number is better.
The bats are a bit of a useless enemy though, at least let them fly in your direction and when hit subtract health. Right now they're just cannon fodder. :P
I'm also working on an FPS, trying to keep the scope small, I think you did a good job on that.