GitHub.io is a domain used by GitHub Pages, a service that hosts static websites directly from code repositories. Developers have uploaded "clones" or ports of the original (the free, browser-based version released in 2009) to these pages.
To understand why this method became so popular in 2021, you have to understand how network firewalls work. Schools and offices often block gaming sites and specific URLs (like minecraft.net ). minecraft unblocked githubio 2021
The phenomenon of via GitHub.io represents a unique intersection of gaming culture, open-source technology, and the ongoing tug-of-war between institutional network restrictions and student ingenuity. By 2021, this movement reached a peak as developers leveraged GitHub's hosting services to bypass school and workplace filters, providing a browser-based "Minecraft" experience that required no installation. The Rise of Browser-Based "Unblocked" Minecraft GitHub