Sonic the Hedgehog CD (Sega CD)/Special Stage

This is a sub-page of Sonic the Hedgehog CD (Sega CD).

To do:
Document more stuff from the Special Stages.

Secret Stage

As mentioned here, setting all three Sound Test selections to 07 will load this stage that features the enlarged head of Robotnik as its background and has a rather difficult layout. Completing this Special Stage will display a secret credits screen.

According to a former Sega Europe QA tester, an eighth Time Stone was originally collectible here. When collected, the ring monitors in every level would be replaced with the unused "S" monitors, granting the player invincibility and a speed boost.

(Source: Sonic Retro)

Unused Graphics

Sprite	Description
	An animation of Sonic doing his classic foot tapping.
	An animation of Sonic being pulled up by... something. Purpose unknown. An early screenshot shows a hot-air balloon, instead of UFOs, in the Special Stages; perhaps they caught Sonic and floated him around?
	An animation of Sonic slipping and sliding. Possibly could have been used for when Sonic slips on an oil tile.
	An animation of Sonic looking down, turning around, shrugging his shoulders, and then (partially) sinking, all while having a disappointed look on his face. Concept art for the game that features these sprites confirms that he is indeed supposed to have a disappointed look on his face, so it could've been a "failure to obtain the Time Stone" animation.
	Animations of Sonic leaping and making a landing. Possibly intended to be triggered when Sonic bounces on a spring, since springs outside of the Special Stages don't put Sonic into his ball form, but springs within the Special Stages do.
	A completely unused sprite for Sonic's jumping animation. It has no mappings/animation data attached to it. This sprite was later recolored and reused for Knuckles' jump ball animation in the Knuckles' Chaotix Special Stages.
	Oil slick graphics are loaded in for Special Stages 1, 2, 4, 5, and 6, presumably with the idea of causing Sonic to slip. These can be found normally in some prototype builds, but are unused in the final game. They are non-functional in every known build of the game.
	An unused graphic depicting a hand. The yellow outline makes it likely that this would have been obtained from the UFOs, along with the rings and Speed Shoes. Purpose unknown, but may have stopped the timer and/or UFOs.

Unused Background Chunks

There's a number of unused background chunks for the special stages that appear to extend from the ones that are used. It's possible that they intended to use 1,024-pixel-wide backgrounds but didn't have enough VRAM to pull it off, so they chopped the backgrounds in half. If that was the intention, then possibly, for stages 1 and 7, the chunks would have alternated (1st chunk from used background, then 1st unused chunk, then 2nd used chunk, then 2nd unused chunk), while the rest would have placed them after the used chunks.

Special Stage 1: