For reference Raph Koster wrote "the book" on game design, and was the lead designer for Ultima Online (among other things) https://en.wikipedia.org/wiki/Raph_Koster
Raph was the lead game designer on SWTOR a game that was way ahead of it's time and one of the most enjoyable sandbox mmorpg's I've ever played. I'm working on a new game that will take inspiration from lessons learned there.
1: https://www.raphkoster.com/2007/09/18/metaplace/, or this demo https://www.youtube.com/watch?v=tZiB_JcRH_s, or https://en.wikipedia.org/wiki/Metaplace