Interesting concept! However it's sad there is no sound and it isn't a bit more polished, its quality would improve a lot to me with a few things! Sound when you shoot, when you get healed, when you lose, when you win, and a music loop would be great. HUD displaying to your screen, or at least a message telling you to go fullscreen. Another detail, I wondered for some time if there was a point on having the two spawner different colors? Not even sure what they are supposed to be xD Also I think you missed the theme a bit, unless it was intentional to take it on a wider sense.
On the positive side, I love the purple going everywhere when I shoot, and screenshake when shooting, good feedback. The HUD is quite clear too.