I stumbled on Project Zomboid one day, and something about it caught my interest. It's still early in development, and they have a deal like Minecraft where people who sign up in Alpha will continue to get updates and help contribute to the creative process. What makes this different from other zombie games I've played (Most often with my brother who's a fan of zombies. A very big fan.) is part of the premise: "This is how you died."
It reminded me of an article I read a long time ago about some old school games, especially shooters, "It's man versus machine. You know the machine's going to win, but the question is how long can you last?" Project Zomboid has no win conditions, and fittingly, it has a "sandbox mode" right now.
For the zombies themselves, the creators look towards Romero for inspiration. An individual zombie slow, stupid, and easy to splatter with a baseball bat, but you can't last forever against a horde. They're attracted to light and noise, so carrying a flashlight and firing your shotgun are generally unsafe actions. Once, while I was hiding in my safehouse, I ran instead of walked and ended up making a small thump which attracted a zombie to bang on my door, which subsequently attracted the nearby mob. I had to abandon that safehouse and run for another shelter.
Right now, the game is very solitary, but the creators plan to create more interactive NPCs. Once they have that going, the real danger may very well be your fellow humans. Got scratched by a zombie? The gun nut might prefer to shoot you now, rather than waste food on a potential zombie in the making. Hyperactive kid making lots of noise? You've got a decision to make about whether or not he lives.
Aside from keeping your belly full in the current version, there are psychological mechanics in the works. Staying indoors for days at a time causes boredom, making it worthwhile to grab newspapers and magazines along with other supplies. Psychological effects will build up into dangerous things like hallucinations and other insanity.
As I was typing this post, news on a big update comes through my brother. Things are going to get a bit more interesting. I should probably keep my food closer to my bedroom if NPCs are going to actually going to 'play the game' now.
...I hope they fix it so that I can get wood from barricades back when I take them down.