Asklemmy

CDDA is a 2D top down roguelike survival game, set in an apocalypse where zombies, aliens, hellspawn and so many other horrible things have shown up everywhere and completely pushed back humanity to the brink of extinction. There are so many real world items like specific gun brands and models, foods with lots of recipes to make bigger and better meals with, recreational drugs tucked into drawers and the pockets of felled zombies.

You could play like a survivalist hobo out in the woods living off the land away from all the carnage and sipping pine needle tea all day while tending to your crops, or explore cities overrun with undead and using night to cover your tracks as you hop through open windows, climb up downspouts and leap from roof to roof. Or you could head down into secret labs to loot cybernetic implants and mutagenic compounds to become something more than human.

You could do quests for NPC factions and also build a team of NPC followers of your own so that you can (over a long period of time and a significant resource investment) build up the structures in your own custom settlement, sending your followers out on missions.

Or you can find enough materials, tools, vehicle parts and mechanics skill books, to become a master mechanic and build up your own custom armored super car, once you tire of walking or bicycling everywhere or driving a bog standard sedan you fixed up off the road.

The controls are very complicated, and if you're the type to get mad when the devs change or nerf something you were used to, you'll be pissed a lot. Some of the things I said may not even be accurate any more, I know custom vehicle construction got way harder after the last time I played, among other things, but otherwise it's one of the most intricate and complex games out there, in a usually fun way, with very good mod support.

Open source game: https://cataclysmdda.org/releases/