It's (by far) my favorite zombie game but sadly was a amateur project and was canceled
, but you can still download the demo from here (have just googled it):
I love it because it was in my opinion very very well thought: you move in a top-down view, which works great for strategy and there is first person for shooting. There are different characters with different attributes, like speed, morale, aim... and one bite kills you. There is inventory, different weapons, you can lock behind doors, visibility lines...