Cataclysm: Dark Days Ahead is the most realistic game ever made. No other game had made me ask "what would I do in real life?" before. Of course, this dies out the more you learn the meta, but your first dozen or so runs are special.

There are some other games that I'd call somewhat-similar. There's that old Finnish game, whatsit called, is kind of similar in that it's a wilderness survival roguelike. An innawoods run in Cataclysm can play kind of like that, though Cataclysm as a whole is a lot larger.

kagis

UnReal World

It never quite grabbed my interest the way Cataclysm has, but a lot of people like it. Huh. Apparently it's not that old, though it goes for a Win95-era appearance.

Cataclysm, for those who haven't played it, is a very complex open source open-world roguelike. The modeling of a lot of things, as the game has grown over the years, has become remarkably sophisticated, from local weather systems to things like very extensive (realistic, not like Borderlands guns) gun modding, vehicle (land, sea, air) creation and modeling, farming, NPC camps, cybernetics, mutation, sound/smell/sight tracking enemies, martial arts including weapons forms, skills, proficiencies, various types of real-world (and supernatural) diseases and parasites, brewing, modeling of fires, modeling of pain, temperature...it's a bit of an organically-grown mishmash, but it's become a game with an enormous amount of mechanics, albeit a very graphically-simple one. I would definitely recommend it to someone with the time and willingness to explore the game's systems, which is not for everyone. You can just download builds yourself, or there's a commercial version on Steam, if you want to support the developers.