If you control the browser, install "Ultraviolet" or "Holy Unblocker" extensions (where permitted). These create a dynamic proxy that makes the school firewall think you are visiting Google Docs, while actually rendering Powerline.io.
The game itself is a masterpiece of minimalist design. The unblocked version preserves 99% of the original gameplay experience: the same physics, the same competitive leaderboard, and the same addictive "just one more swing" loop. For students stuck in a study hall or office workers on a slow afternoon, is a lifeline to quality entertainment.