Thank you!
XR wise- I'm not the most informed but I've had a lot of fun exploring VR Chat on private servers with friends
Non XR-
HORIZON which I developed for the Guggenheim museum
A bunch of wonderful LIKELIKE-likes, 2d web based MMOs, ours is called the Biome Gallery
One of the first spaces we explored together was Red Desert Render, which was super inspiring in terms of multiplayer movement and discovery
Our friends over at Sickhouse / The Overkill are always exploring these kinds of spaces live on stream, with audience participation - check out their "Exploration Mode" series for tonnes of great recommendations
We were hanging out in v buckenham & Viviane Schwarz's Frog Pond last night
There are probably loads more but that's just off the top of my head, hope it helps!