There's a lot wrong with this. Let's start at the top:
1. First you're given three gun choices and three map choices. There is no label on any of them, but if you choose the right two of either, it tries to make an in-app purchase. Shady technique to say the least.
2. The controls are ill placed, and the operation of the controls leaves a lot to be desired.
3. The graphics are weak. The map is bland, a terrible layout, and the edge graphics had very little effort put in to them.
4. Probably the most crucial part, the game is not playable. What I mean by that is there are 18 zombies to kill, and something around 30 bullets, with no ammo pickups. The glaring issue is that it took me around eight direct head shots to kill one zombie. Do the math, you can't ever win. Not worth the time to write this review.