An "unblocked" version refers to a mirror of the game hosted on a site that isn't recognized by the firewall, or accessed through methods that bypass the restriction.

Many unblocked sites host community-made levels that aren't available in the standard version, offering a fresh challenge for veteran players. Tips to Dominate the Leaderboards

One wrong move leads to an instant restart.

He clicked the link. The game loaded instantly. No splash screens, no lag. This was the "better" part of the equation. It wasn't just about getting past the firewall; it was about optimizing the experience for the restricted environment of a school Chromebook.