I always thought of it as something that works the same as DayZ where you can group up and try to survive the zombies and loot empty houses, or you can try to hunt down fellow survivors to get what you need from them. So it is neither only co-op, nor pvp but a little bit of both... Dayz is built off of a 3rd/1st person shooter though, where pvp boils down to gunplay who's the best shot etc. PZ would just be, who can click on the other quickest. Not slating the game at all, I adore PZ.