I feel like the best options would be strategy such as CK3 as the other commenter mentioned or endless sandbox games like Minecraft and Euro/American Truck Simulator. X4 Foundations is a pretty fun space sim, and there are the Bethesda games with mods, Skyrim and Fallout 4 have some pretty cool mods and eventually Starfield too.
They are all decent, and fun to play if they’re your jam, some are more pay-to-win than others, like Star Trek Online. Some are a bit on the older side, like Guild Wars 1 being from 2005 though.
The Age of Decadence is CRPG set in a post-apocalypse ish, in which an analogue to the Roman Empire ruled most of the world until the collapse of civilisation, now it’s mostly city states struggling to survive and reclaim the old magitek of the empire.
Underrail: Life on earth’s surface has been made inhospitable ages ago, and the remains of humanity now live in the metro system called underrail and the caverns around it.
Both are isometric, turn based games that focus on combat and exploration. And they are hard. Builds are incredibly important, almost min maxing but they have a wide range of viable builds, especially the first one where you can play the entire game without fighting a single battle, all through alternative solutions and skill checks.