If you are on a restricted network (school/work) and looking for legitimate games that can run in a browser via GitHub repositories, consider searching for:
Similar to VPNs, proxy servers act as intermediaries between your device and the internet. They can help mask your location, but they might not be as secure or effective as VPNs for gaming. ultrakill unblocked github
If you are looking for more than just a way to play at school, GitHub is the central hub for the game's most advanced mods and custom tools: If you are on a restricted network (school/work)