I've always been curious about real-time multiplayer user interfaces.
When I found out about CRDTs and Yjs[1] I thought they could serve as a solid base for a project like that.
So I built this pretty simple desktop-like UI (heavily inspired by lifeat.io) and used Yjs to replicate the whole UI state among multiple peers, creating the experience of a unique interface.
Try online: https://yboard.lol
[1]: https://github.com/yjs/yjs