Sonic the Hedgehog CD/Hidden content

Lost Sprites

Artwork	Name	Description
	Sonic with eyes closed	An unused sprite of Sonic with his eyes closed. Could have been used as part of an idling animation, akin to Sonic 2's two stages of waiting, and Sonic 3's unused animation of Sonic nodding off to sleep
	Sonic being electrocuted	An unused animation of Sonic being shocked by electricity. It may have been used in Wacky Workbench, which contains various level elements with the potential to electrocute the player. It could also have been used in Collision Chaos, as part of the Metal Sonic sequence.
	Sonic falling	An unused animation of Sonic falling into the distance. Purpose is unknown. A similar animation was found in Sonic 1 which was also unused.
	Sonic waving his arms	An unused animation of Sonic waving his arms with his palms outstretched. This could have been used in Tidal Tempest when walking through the water, to simulate an attempt at moving more quickly.
	Sonic looking backwards	An unused sprite of Sonic looking over his shoulder. Purpose unknown.
	Sonic sneezing	An unused animation of Sonic sneezing. Purpose is unknown. There is a scene in the opening cartoon where Sonic looks up and then sneezes, easily seen when watching frame by frame. This could possibly mean that the cartoon may have at one point in development been sprite-based, but this is unlikely.
	Sonic upside-down	An unused animation of Sonic upside-down with his eyes wide and his mouth open. This suggests that this animation could have either been used for an alternate death animation, or if Sonic was caught by an environmental hazard that dangles him in the air somehow.
	Sonic grabbing	An unused sprite of Sonic grabbing onto something and attempting to create traction. This implies that he may have been trying to stop something from pulling him into some sort of hazard. Part of a scrapped badnik, maybe?
	Sonic on horizontal pole	Similar to the other horizontal pole sprites from Wacky Workbench, this one has Sonic swinging his feet forward. Perhaps he originally had to pull away from electrical hazards positioned underneath.
	Sonic shrugging	An unused animation of Sonic shrugging his shoulders. Note that his spikes rise during each frame--many believe this implies a transformation into Super Sonic, though such a notion is purely speculation. These sprites are found in the SPSS__.BIN, which contains Sonic's special stage specific sprites. In the final frames of the animation, the very bottoms of his feet disappear, as though he is sinking into something. Perhaps an unused quicksand hazard, or even being pulled out of the special stage altogether, as a failure to obtain the time stone animation.
	Sonic hanging	An animation of Sonic being pulled up by... something. Purpose unknown. These sprites are also found in the SPSS__.BIN. Early beta shots show hot-air balloons, not UFOs, in the Special Stages. Perhaps they caught Sonic and floated him around?
	Sonic falling back	An animation of Sonic being knocked back. Purpose unknown. These sprites are also found in the SPSS__.BIN.
	Sonic leaping	Purpose unknown. These sprites are also found in the SPSS__.BIN.
	Sonic with chest forward	An unused animation of Sonic with his arms outstretched and his chest pushed out in front of him. Whilst its purpose is unknown, many believe that this is somehow related to transforming into Super Sonic.
	Sonic skidding	An animation of Sonic skidding whilst looking the other way. It is unused in the main game, but does appear during the "You Are Greatest Player!" sequence seen once beating the Time Attack scores. It's fairly similar to the skidding animation in Sonic Crackers, and could have been used while skidding at higher speeds in contrast to the normal skidding animation, which was modified from Sonic 1.
	Unused Amy sprites	Unused sprites of Amy with hearts in her eyes. Not used at any point in the game.

Level Objects

Artwork	Name	Description
	Oil Slick	Oil slick used in special stages that cause you to slip. These can be found normally in some prototypes of Sonic CD, but are unused in the final game.
	Broken Switch	An unused broken switch sprite found within the ROM. Speculation shows that they may have been used in the bad future of a zone, to prevent access to certain routes. Other switch sprites for comparison.
	Platform	An unused platform which moves up and down while moving to the left. It comes in two variations; a pair and a group of four, all of which do the same thing (though in the latter, the top row are flipped vertically). The object belongs to the present version of Quartz Quadrant Zone.

Extra Special Stage

An extra special stage can be accessed from the Sound Test menu by setting all the 3 selections to 07. According to a former Sega Europe QA Tester, an extra Time Stone was to be collectable here. When collected in addition to the previous Time Stones, "S" TV monitors would appear where the ring TVs were previously located. When broken, you would morph into a gimped version of Super Sonic, which would simply grant you invincibility and greater speed. Graphics would not change.

Time Attack Icons

Two Time Attack icons show differences from the final game. The Quartz Quadrant icon shows purple crystals in the foreground. These are not found in final, but are present in the 510 proto, but green in color. The Tidal Tempest icon shows ripples in the foreground. In final the ripple effect is only applied to the background. The 510 proto has the ripple effect in the background.

• 

  Quartz Quadrant icon.

• 

  Tidal Tempest icon.

Unused Music Loops

Within the ISO for one of the Sonic CD prototypes were some specific files, preceded with the letters "SNCBNK", with a number afterwards. The numbers referred to the timezone for which the file represented.

Each file is a small music loop, played using the PCM chip on the Sega CD, in accordance to the timezone it represents. Speculation has been rampant as to their use, but two theories have stemmed that seem to be relatively plausible:

• They were intended to be used to bridge the gap between when a CD audio track plays and when it starts again.
• They were intended to be played at the start of a level, before the CD audio played.

Of course, there's no concrete evidence to support either idea, but it's an interesting debate nonetheless.

Get the files here ^(info) (1.97 MB), courtesy of ICEknight. Get Shadow Hog's edited files merged with the CD audio tracks here ^(info) (33.56 MB). Check out discussion of this oddity in

this forum topic.

Prototype Music Tracks

In the 510 beta of Sonic CD, there were two distinctly different music tracks not featured in the final version of the game. scd510_28.mp3 is an alternate speed shoes track, while scd510_25 is an alternate title screen track.

Get them here ^(info) (922 kB).