Dwarf Fortress is a single-player fantasy game. You can control a dwarven outpost or an adventurer in a randomly generated, persistent world.
What it lacks in graphics it makes up for in complexity. I’ve always been too intimidated to play Dwarf Fortress but hearing stories like “we had to improve cats’ livers because the dwarves were spilling their drinks and the cats were drinking the puddles and dying of alcohol poisoning” puts it up there with EVE or Factorio as something I’d love to have the time to dive into.
While they did a paid Steam/Itch.io version recently with fancy graphics, the original is still free to download.
It doesn’t take up that much time
Just buy the steam/itch version (no, you won’t have a great, user friendly experience starting with the ASCII and it supports the devs), and watch Blind’s tutorial and quick tutorials if you find something cool there. They are excellent and easy to watch. Also, note that if you ever played Rimworld, DF is at a much larger scaale and is overall easier. Yes, even accounting for the -spoiler–>
Tap for spoiler
circus and the bozos