This does a great job of feeling like a complete game with a nice, consistent art style and all the music and sound effects you would hope for. Nice touch with the splatter remaining for a few seconds - reducing the speed of the particles to zero?
It would have been nice to have a second button to do a special attack every 10th zombie or something like that. But you did find a use for the space bar so it's on theme.
I had a couple of goes at this one, I like the rate at which the challenge ramps up, well balanced.