It’s a parallel timeline mod similar to Better than Adventure. It’s based on Minecraft Alpha. https://github.com/BlueStaggo/MCDiverge

It’s Moshidon

https://addons.mozilla.org/en-US/firefox/addon/uaswitcher/

Ubuntu. If I remember correctly it was in 2016. I do remember that it was still using the Unity desktop environment, which was pretty good in my opinion. I didn’t know anything about Linux back then, and I tried to run Minecraft on it through WINE. It didn’t work lol.