It would be hard to understate the influence of Bethesda's Elder Scrolls 3: Morrowind. I originally played it on the original Xbox back in 2002 - an absolute eternity ago.
While doing research, I found this fascinating comparison between the various Elder Scroll games. You can really see the jump in graphics with Morrowind. It may not have been the first game to incorporate the underlying elements, but the combination of graphics and launching as one of the very first RPGs for the then brand-new original Xbox made it a hit.