Did I pay a dollar, two dollars? I don't remember. It's a neat app, mesmerizing at times with the new update (adds soldiers, helicopters). It's an interactive experience now—much less passive, but there are still no objectives.
Expect minimal gameplay at best, but given the crush of IAP-driven game design overwhelming and ruining the Apple Store environment, the lack of any pressure is nice.
Couple of things I would like to see in future updates, if they happen:
--- A way to lure zombies towards a location on the map, to make the simulation last longer, because the zombies are mindless and get stuck after the initial onrush
--- Polish for the "indoors" mechanic. Zombies and civilians can spawn inside a building, but generally they cannot leave the building and generally anyone on the outside of the building cannot get inside.
Basically, I want to see total simulated annihilation and can't consistently get there because the AI is often so mindless that it doesn't hunt outside of a relatively small radius. This goes for the living as well as the undead.