Birdpals is a virtual world that I'm a developer of. It was started by Penguin Giraffe.
The game started being made in Unity, as that was the engine I was most familiar with at the time, but I was using an online framework called "Mirror" for it, and it was hard to make a standalone server for the game. And so, we switched to using Javascript and socket.io
The project was a sort-of successor to Dentopia, which you can find out more about here.
If you want to know more about Birdpals, you can check out the wiki.