Project Zomboid is an open world sandbox survival RPG. Calling it a survival game might be a little bit of a misnomer though, because there are zombies and other hazards, and eventually you will inevitably die. Whether it's the undead that do you in or one or more of the other situations you will be battling during your adventures changes each time. You will be able to create your character, choose a profession, and assign traits to round out who you're playing. The catch? You'll have to take a negative trait even just to get your initial positive one, and the game continuously encourages building layered characters.
You could be a cop with lots of firearm knowledge and a hardy constitution that's also agoraphobic and thus might suffer mental strain if you have to hide in enclosed areas like bathrooms or sealed rooms. Hunger or thirst can get you too. And that's before considering the zombie threat. Project Zomboid, can be played solo or on open or private servers, adding to the danger and drama by letting you play with buddies. Multiple modes also add to the replayability.