Good idea, needs way more polish
I was really enthused by this game at first, but a lot of problems started to manifest after my first playthrought - mostly with the upgrade system. The upgrades simply increase the variety of weapons you can have, but not the drop rate, which actually limits your tactical options because it makes the particular weapon you want less and less likely to drop next. The fact that there are no upgrades other then "new guns" and extended clip sizes is doubly frustrating, because it never feels like you're actually improving or earning anything. As I said, more choices is hardly a reward, and the extended clip size is even less useful, because I found it often left me in the uncomfortable position of either finishing up my current clip, or picking up the new "fresh" weapon that was more tactically advantageous - either way, I waste a weapon and don't really see an improvement from when I was at rank 0.
Worst of all is the inclusion of the riot shield as a drop- this thing is no weapon, and all it's good for is stalling until a real weapon drops. So unlocking it actually makes the weapon drop roulette even crappier than before. What's worse, it happened several times where a riot shield dropped twice in a row, meaning that I had absolutely no real weapon (even the machete might be better) for a very long stretch of time, while zombies closed in on me to the point that survival was impossible. A poisoned upgrade, made even more insulting by the fact that it slows you down to "balance" the oh so precious gift of being able to defend a single side while doing laughable damage to zombies who are all too eager to just clip through you if you aren't standing perfectly still while bumping them.
Basically, this game is only worth the first playthrough, and it's shocking how little testing must have gone into the so-called upgrades. My first score was by far my best, and I doubt my experience is unique. If a sequel comes around and actually uses a real upgrade system - increased damage on weapons, increased speed of swinging the melee weapon, increased health, more frequent power-up drops, things like that that actually make the player stronger instead of just making him spin more and more plates as a "reward", then I'll gladly give it a try. Until then, this game only held my attention for 10 minutes. Blah