It sounds like you're looking for a way to get Retro Bowl running on your Chromebook, even though the standard "unblocked" sites might be getting patched by your school's network.
If your Chromebook supports the Google Play Store and your admin hasn't locked it down: retro bowl unblocked chromebook patched
A few tech-savvy users saved the entire Retro Bowl web page as an HTML file on a USB drive. The theory is you plug the USB into the Chromebook and open the file locally. It sounds like you're looking for a way
Notable community features/mods
Why it works: These pages often fly under the radar of standard web filters. 2. Chrome Web Store Extensions retro bowl unblocked chromebook patched