Okay it was rushed as you said but:
You needa make it so you can move about a bit like a change of scenery.
And maybe more than one type of zombie.
You could also make a money/shop system so it's not so "UnSurvival"
Then it'd be excellent.
Also that shotgun is aweful, it shoots at like 45 degree angle so it doesn't hit anything alot of the time even at close range.
Oh oh, and it did some auto low quality thing after a few mins, was a bit weird. :s
Anywayy good start.