Great game, I liked the music. I'd suggest preventing enemies from firing until they're visible on the screen as it's a bit hard to fight back when you can't see them. Other that that a nice well rounded effort.
Thanks! I debated to myself about firing off screen, but I really liked the 'shocking' effect. I wanted it to make things feel slightly overwhelming to add to the tension. It might be a little too far off screen though! Glad people are liking the music, it was a lot of fun to come up with.