Its a great start, that's for sure
I think that if you updated this, you could make it into an incredibly fun and awsome game.
My main problem with this is that the zombies come in on parachutes, however, killing them en masse means that you build up a tower of bodies. Scaling the tower of bodies is fun, but serves no real purpose as it only brings you closer to the zombies spawning at the of the screen.
Therefore, to stay away from them, you have to stay near the ground, meaning the corpse climbing mechanism is pretty pointless.
If you were to change it so that the zombies came from either side of the screen and still piled up, I think this game would be much more worthwile because then piling the bodies up actually serves a purpose
(You are now much higher than the zombies, and it takes them longer to get to you).
But of course, the art is good, nice powerups and stuff, and because of that I can see that this game has lots of potential. Keep up the good work, and I hope you make a sequel to this.