I made an idle version of the 1999 MMORPG "EverQuest". There's maybe around 50 people playing at any given time and has a enthusiastic discord group for it. It's relatively fully-featured to the original game, and has a lot of new mechanics to make the idle format work well. The 3D graphics aspect of it is really more of a screensaver, though, and all game interactions are done through menus.

I recently converted a bunch of stuff to be client side instead of server side (turns out running a real-time MMORPG server is expensive) so there's a new round of bugs I'm still resolving, but it's still fun to play:

https://www.idlequest.net/