Graves Robber is a fun 3D shooting game. There are loads of Zombies everywhere in the large and fully 3D environment. It also has cool RPG elements with all sorts of upgradable weapons and armor which you have to save up money to purchase. There are even boss monsters that have to be killed with in different ways. The controls are a combination of d-pad and accelerometer. There is even a lite version available so that you can try it out.