So I've spent the past month I've been playing Project Zomboid and have decided it will likely be one that I will mod the poop out of. (Along with Don't Starve. I clearly have a bias towards survival games...P.S. I'm thinking of making a survival/adventure game)

projectzomboid.com/

In any case, go buy this so they can make more game faster. With the Steam update, they've added a second map along with a load of other new items and functions (Like bacon...mmm, bacon).

Insofar, the longest I've lasted was a game with Devon where I was closing in on 4 months of survival. The game was lost when I updated, so I never got to see him die, just fill his house with a thousand journal pages and stare out the window for days on end, waiting for Raleigh and Astoreen to come back one day.