My two biggest projects are:

https://www.idlequest.net/ - a from-scratch recreation of the 1999 MMORPG classic EverQuest, featuring a real-time MMO server written in Go, a 3D game browser-based client built with Babylon.js, and the clasic UI recreated using React. You can play it both as a regular MMORPG but also in "idle mode" where it basically plays itself. This had up to 70 players online at once a while back which was really cool, though its popularity is in a bit of a lull right now. There are still tons of bugs and stuff that isn't fully implemented (and balance issues) but it's still fun for most people who have nostalgia for it.

https://www.newyokosuka.com/ - an unofficial Shenmue MMO experience. Based on the 1999 Sega Dreamcast game Shenmue, it's playable entirely in your browser! It's basic world exploration with forklift shenanigans, some basic dialogue systems, and a basic combat system test, but I'm about to push an update that includes all cutscenes and story progression as well. The story part is taking a bit of time because I'm having to mold it to fit in an MMO context. But it's a fun project to work on and the Shenmue community loves it so far.