GitHub.io is a domain that GitHub offers to users for hosting static websites directly from their repositories. Because it is a legitimate platform used by millions of developers for portfolios, documentation, and demos, network filters often overlook it. Clever developers have taken advantage of this by hosting simple HTML5, JavaScript, or Flash game emulators (like those for classic arcade, NES, or browser-based puzzle games) on GitHub.io pages. When a game is hosted there, it often bypasses typical web filters, hence the term "unblocked."
| Component | Implementation | |-----------|----------------| | Platform | Chrome / Edge / Firefox extension | | Storage | IndexedDB (games) + chrome.storage.local (metadata) | | Offline capability | Service Worker + Cache API | | Allowed origins | *.github.io , *.gitlab.io , *.netlify.app (configurable) | | Size limit per game | 100 MB default (user adjustable) |
Appendix A — Minimal local-hosting steps (authoritative, safe)
Appendix B — Risks checklist before running third-party github.io games