There are a lot of zombie games out there, but they tend to focus on human-vrs-human violence with the zombies as an afterthought, or one-off battles with the undead, usually in a dense urban setting.
County Road Z is unique because it returns the focus to survival and cooperation against the zombie menace in a rural area. That means building a base for your survivors, staffing your kitchen and infirmary, building up some working vehicles, etc. Then, when you do go out to battle the hordes, it's for a purpose; you need food, medicine, supplies to improve your base, and of course, rescuing stray survivors. Because, in County Road Z, other people are a vital resource, not always a rival gang to fight.