Plays inside your own copy of Minecraft: Java Edition, on your device, not in a browser tab. Opens github.com in a new tab.
How to play
Have your own copy of Minecraft: Java Edition 1.16.x installed: the mashup plays inside it.
Download it from its release page on GitHub.
Install it as its page says. What it asks for is just below, in the list's words.
Start the game the way its page says: some mashups come with a launcher of their own.
What it asks for
Fabric Loader and Fabric API on Minecraft Java 1.16.x (CurseForge lists 1.16.3 for the 1.3.x files). Client-side only; the README says it will not work when Minecraft runs from a network drive because it uses memory-mapped files, and multiplayer is disabled in the nested game.