Bugged
Never even got to the first boss. Got a zombie stuck on my radar sometime on wave 13 that wouldn't come into view and just kept moving as I moved. Restarted got to level 14, at the beginning of which I got about 7 or so radar contacts that kept moving with me but were never visible and then the rest behaved normally.
Anyways, this game has been done before a million times and has been better and more original, that being said it's not half-bad. It's just all around "meh". Also way too easy. Stuck with the pistol all the way through wave 14 and was gonna use the minigun on the 15 boss just for laughs, but alas never got there.