Hidden Palace Zone

Sonic The Hedgehog 2 / Sonic The Hedgehog 2 Beta

Hidden Palace Zone is the most famous of the "lost levels" from Sonic 2 Beta, mainly because it remains in a corrupted form on the final version of the cart. It is an underground level with water, featuring sparkling Gems. Many parts of the level were once grounds for debate, such as the "master emerald", but most theories have been generally accepted as false. Some hacks, like Sonic 2 Delta, have restored the level using the graphics from the beta version and level map and object data from the final releases graphicless version.

Hidden Palace Zone contains a glowing bridge (object number $11) that is actually the same object as the bridge in Emerald Hill Zone but it checks the level number to make it glow. The idea of a bridge that will glow when Sonic runs on it was reused in Sonic 3's Icecap Zone.