I think this is one of the best apps ever. The only thing that could be improved is the balance of some items. Especially the health-kits are overpowered. It doesnt matter if you take damage or not if you can fully heal within a second. Suggestion: you can never have more than one kit that recharges all 20 secs and not by picking up ammo. upgrades improve the recharge rate and the amount of healing it does.
Another thing that would be quite nice is an endless mode that goes on until you die.
However, i strongly recommend to get this app. It is great
Doodle.64 about Zombieville USA 2, v1.3.3