The first game that comes to mind for me is Civilizations 4. I’ve probably spent hundreds of hours playing but after getting used to 5 and 6 I have a really hard time going back. Going back and forth between 5 and 6 I need to rethink some strategies but with 4 I feel like I need to rethink everything. I don’t know if it’s because of the tech tree layout in combination with the civics system, things like unit stacking, or maybe just a bunch of little things but it takes me a while to readjust.
Well, I’d say Morrowind is still decently playable today, esp. with OpenMW. Sure it shows its age, but I’d ratber play that than e.g. Oblivion.
I might give it a go, I believe it fixes the exploit where you can increase the stock of merchants with restocking ingredients, which makes alchemy a cake walk, no ? I could never resist that