I didn't have much fun with Project Zomboid. I found that the game played a bit awkwardly.
I would personally recommend Zafehouse Diaries a lot more. It's a bit different, being a bit of a mix between a strategy game and a choose your own adventure game but it's got a lot more depth than it seems to have at first glance.
State of Decay is also pretty awesome, though light on the RPG side as mentioned above.
If you're ever lucky enough to join testing, the guy who made Garry's Mod is making an MMO called Rust that's showing some potential so far, although last I played, even with so few players, resources were really, really limited as were the zombie encounters.
Lastly, I've been hearing a lot about 7 Days to Die although it is a lot more expensive.
Post edited September 29, 2013 by johnki