Walkie
This is an in-browser Walkie-Talkie: you open the page, say your name, and see who else is in the room. Click on somebody and a direct WebRTC voice call starts between the two browsers, with no server in the middle.
The server only introduces you. It carries the offer and the answer from one
peer to the other and then steps aside, so the audio never goes through it. That
is also why it stayed down for six years: nothing was broken in the app, the
introducer had simply gone away.
The room is the URL hash, so #kitchen and #garden do not hear each other.
You will need a microphone, and two people.