Dayz kind of games are more fun with friends (I played Infestation: Survivor Stories and Unturned among others but they tend to become boring :S) I usually prefer games with some history or meant to be like levels (No more room in Hell, Contagion, Left for Dead…) Anyway, lately I've been checking "Dead Frontier 2", it has been recently released in Steam (Free to Play but Early Access) which looks interesting enough, so it might be worth the try.

And I heard State of Decay was pretty good! I think it is a good choice, I'll check it, thanks! :D