Pretty nice idea, I liked the way it felt. Audio and visuals were on the spot!
I suggest giving some kind of penalty for pressing the wrong button many times (or maybe something else). Because in the end, I realized that you can press all of the four buttons simultaneously, so I could keep shooting without guessing which button is the right one.
One bug I found is that if you go to one side of the screen and press space a few times you get stuck outside the borders, you still able to take damage but unable to get back in the camera view.
Overall, I think it is a great entry, good job.