As a personal project, I made SkyOffice - pretty much a Gather clone (office version), and I built it with Colyseus, React/Redux, Phaser, and WebRTC/PeerJS.
In SkyOffice, you can work “alongside” your colleagues. If you walk close to other players, a video call connection will be made (remember to allow the browser to access your webcam). The call will be ended when you are not close-by the player anymore. You can also use a “computer” in the game to share your screen! Two people can even share screen at the same time (pair sharing mode) if they are using the same computer.