UO has a super robust eco system of private shards and server software. It’s kind of amazing. Pretty active development on things like ServUO or ModernUO servers. The client has been fully rewritten and actively developed with improvements on ClassicUO. All of these are open source as well.
For servers you have places that function entirely as different eras of UO like the Renaissance shard, or even entirely new content like what’s in Outlands.
There’s honestly a lot to be found out there and it’s really neat.
I managed to soft lock the new Pokemon Snap game in the tutorial where they had you take a picture of a Butterfree (I think is the right Pokemon). Somehow when I took a picture, it flapped its wings and turned enough that it was flat in the picture and couldn’t be selected when you were at the next phase of the tutorial selecting the shot to show the Professor Oak stand in. You couldn’t go back to take another picture, so I was effectively unable to continue the game from there. I was pretty proud of my bad picture taking skills.