The entire Ultima series for sure. I think those were the first CRPGs I played. I loved Ultima: Underworld I & II, but I was never able to get Ultima VII: Pagan to run properly on my computer. (And, holy fuck, that was 30 years ago.)

But also The Elder Scrolls: Arena, TES: Daggerfall, TES: Battlespire, TES: Redguard, and TES: Morrowind. The first two TES games would be challenging to make, given that many of the areas were randomly generated, rather than being designed.