I've been adminning/developing for a small UO private shard for a few years now. It's such a great platform for MORPGs, with only one M and heavy emphasis on the RP (our shard has a strict no-OOC policy).
Sadly the engine is very obviously 30 years old and it's such a pain to develop for, even given all the community tooling that has pretty much reversed everything about it. Even though I love what's built on it and have lots of ideas, implementing those ideas with all the technical limitations kinda sucks. One day I'm definitely going to make my own standalone spiritual successor. Yeah I know, add it to the pile, but this one would be different!