I expected the graphics to be worse. I looks pretty cool, I think. The sound and music is good, too.
My main problem in the beginning was that I didn't get who I was. Maybe the zombies' and the player's appearance could differ a bit more. Also I think it gets boring quite soon, because there's not much happening. Why don't increase difficulty in more ways than just a higher number of zombies? Let the trucks drive on the other side of the road, as well. And it would fit your topic if the zombies spewed blood or something. Maybe you could give the player a second chance, so when a zombie bites you, you loose some blood, but you can go on. (maybe you become slower).
Btw, what program did you use for the graphics?
P.s.: My highscore is 63 seconds, which I'm very proud of They were so many...