I think you just would love Project Zomboid!
It's an indie game and kind of sandbox like. You'll get thrown in a zombacolypse and your goal is just to survive. Of course there are some sidequests. You can build up barricades, weapons to defend yourself, meet other survivors and so on. If you'll get hurt on the leg, get ready to be eaten! The controls are a bit strange, but if you get the hang of it...
I played the demo in an early stage, but scince then there have been some updates, maybe they improved the whacky controls and maybe they have removed stuff I was talking about. You just reminded me with your post.
Give it a try!
http://projectzomboid.com/blog/