Sonic the Hedgehog CD/Hidden content

From Sonic Retro

Back to: Sonic the Hedgehog CD.

For hidden content pertaining to the 1996 Windows release, click here.

Stage select


On the title screen, press Up Down Down Left Right B.

Selecting round 2 is infamously impossible, as the level select just skips to Round 3 (Collision Chaos)

When a level is accessed this way, clearing the level or attempting time travel will take the player back to the title screen. If the level was ended by attempted time travel, entering the stage select again and choosing another level will start the level as if the player had traveled through time, keeping any Rings and accumulated time from the last level.

View developer time attack times

SonicCD MCD Times.png

On the title screen, press Right Right Up Up Down C. The initials may refer to the following:

Move the clouds


On the title screen, hold Down + A and press Up Down Down Down Down Up. The D-Pad on the second Control Pad can now be used to move the clouds around.

Instant death

Pausing the game and then pressing A + B + C will kill Sonic. This is useful for returning to the last checkpoint, or if Sonic gets stuck (which can happen easily due to layout differences between time zones). If this is done when the player has only one life remaining, the game will end and return to the title screen.

In the North American version of the game, only one of the buttons needs to be pressed.

"I'm outer here!!!!"

SonicCD MCD OuttaHere 1.png
SonicCD MCD OuttaHere 2.png
SonicCD MCD OuttaHere 3.png

Wait three minutes without doing anything, and Sonic will say, "I'm outer here!" [sic] and jump off the stage, ending the game.

Sonic's line is commonly heard as "I'm outta here!", though designer Masato Nishimura, who also provided the voice clips for Sonic in the game, stated on Twitter in July 2017 that the intended spelling for the line is "I'm outer here!"[1].

Sound test

SonicCD MCD SoundTest.png

On the title screen, press Down Down Down Left Right A.

Play secret Special Stage

SonicCD MCD SecretSpecialStage 1.png
SonicCD MCD SecretSpecialStage Staff.png

On sound test screen above, set the values to FM07, PCM07, DA07 and press Start.

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, the player would morph into a gimped version of Super Sonic, which would simply grant them invincibility and greater speed. The graphics would not change.

Beating this hidden Special Stage will display a hidden Special Stage Staff screen with the Ending Theme of the game playing.

Secret pictures

Tails' message and edit mode

SonicCD MCD TailsMessage 1.png
SonicCD MCD TailsMessage 2.png

On sound test screen above, set the values to FM40, PCM12, DA11 and press Start. The image was made by Yasushi Yamaguchi, who created Tails, and the Little Planet theme plays on this image.

Tails is pictured next to his favourite carMedia:Sonic2 MD JP manual.pdf[2], the Lotus Super Seven. While seen in a Sega Saturn test disc, this is the only time to date that it has ever featured in a video game.

Edit mode can also be accessed in the PAL version of the game by pressing Start on the second controller when the attraction sequence is playing. The NTSC versions lack this feature (though it is present in the 920 prototype).

The controls for when edit mode is active are as follows:

  • B (Esc in the PC version): Toggles object placement mode.
  • A (Space in the PC version): Selects the next object.
  • C (Both versions): Places the selected object.

MC Sonic

SonicCD MCD MCSonic 1.png
SonicCD MCD MCSonic 2.png

On sound test screen above, set the values to FM42, PCM03, DA01 and press Start. This image was made by Kazuyuki Hoshino, and the theme for Metallic Madness plays on this image.

"Spooky" Sonic

SonicCD MCD Mazin 1.png
SonicCD MCD Mazin 2.png

On sound test screen above, set the values to FM46, PCM12, DA25 and press Start. The message says たのしさ∞ セガ・エンタープライゼス まぢん画 (Infinite fun. Sega Enterprises - Mazin Picture), and was made by Masato Nishimura. The boss theme plays on this image.

Batman parody

SonicCD MCD Batman 1.png
SonicCD MCD Batman 2.png

On sound test screen above, set the values to FM42, PCM04, DA21 and press Start. The image was made by Takumi Miyake, and Final Fever plays on this image.

Anime Sonic

SonicCD MCD Anime 1.png
SonicCD MCD Anime 2.png

On sound test screen above, set the values to FM44, PCM11, DA09 and press Start. The message says ゆーあーくーる by さんちゃんず (You are cool, by Sanchanzu) and was made by Masahiro Sanpei. Palmtree Panic "G" Mix plays on this image.

Backup RAM Error Messages

There are a error messages that can show up if there's a problem with Backup RAM that would prevent saving from properly functioning. The game will only allow you to continue without saving if Backup RAM is full. Otherwise, it'll freeze at the error screen if there's corrupted or uninitialized RAM data.

Corrupted RAM

SonicCDDataCorruptEnglish.png SonicCDDataCorruptJapan.png

Internal RAM Uninitialized

SonicCDUnformatInternalUSA.png SonicCDUnformatInternalEurope.png SonicCDUnformatInternalJapan.png

RAM Cartridge Uninitialized

SonicCDUnformatCartEnglish.png SonicCDUnformatCartJapan.png

RAM Full

SonicCDRAMFullEnglish.png SonicCDRAMFullJapan.png

"CX" room

SonicCD MCD QQ CXRoom.png

There is a hidden room in Quartz Quadrant Zone 1 Past which cannot be reached during normal play. When entering the room with edit mode, the room has glitched floor collision and the letters "CX" in the background made from shadowed tiles. These letters may be the signature of Masato Nishimura, who designed the graphics for Quartz Quadrant, as "CXX" is a nickname Nishimura is occasionally credited under as seen in the developer time attack times screen above, and in the credits for Dark Wizard as "CXXMAJIN".

Time attack icon oddities

SCD TidalTA.png SCD QuartzTA.png

The icons used to denote Tidal Tempest and Quartz Quadrant in the Time Attack menu appear to show earlier versions of these two stages.

Tidal Tempest has ripples in the foreground as well as the background. This is an effect seen in the Japanese version of the original Sonic the Hedgehog, but was removed from subsequent games (including Sonic CD).

Quartz Quadrant has red crystals in the foreground, while in-game the crystals are blue (although they glow a pinky-red).

Unused content


Art Description
SCD electrocuted.png
An 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.
An 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.
SCD looking over shoulder.png
A sprite of Sonic looking over his shoulder. Most likely to look at Dr. Eggman when he activates his laser behind Metal Sonic prior to the start of the race against Metal in Stardust Speedway Zone 3.
SonicCD Sneeze.gif
An animation of Sonic sneezing, similar to what is seen in the opening animation. Sonic sneezing when confronted with danger was a concept briefly explored by Sega in the early days of the franchise, but while a sneezing Sonic appears in some merchandise, Sonic CD is the closest it ever got to appearing in a video game.
An 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.
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. May have been part of a scrapped Badnik. A modified version of this sprite appears in Sonic Crackers, as well.
SCD WW Swinging.png
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. These can be found in Tidal Tempest's sprite data, which also houses several other unused sprites. In the Wacky Workbench sprite data, all 3 are replaced with the final sprites, even in the 510 prototype, so it's possible that this set is the pre-510 version, before they were redrawn.
SonicCD SpecStage Anim07.png
SonicCD SpecStage Anim08.gif
An animation of Sonic doing his classic foot tapping. These sprites are found in SPSS__.BIN, which contains Sonic's Special Stage-specific sprites.
SonicCD SpecStage Anim0C.gif
An animation of Sonic being pulled up by... something. Purpose unknown. These sprites are also found in SPSS__.BIN. An early screenshot shows a hot-air balloon, instead of UFOs, in the Special Stages; perhaps they caught Sonic and floated him around?
SonicCD SpecStage Anim0F.gif
An animation of Sonic slipping and sliding. Possibly could have been used for when Sonic slips on an oil tile. These sprites are also found in SPSS__.BIN.
SonicCD SpecStage Anim21.gif
SonicCD SpecStage Anim22.png
An animation of Sonic looking down, turning around, shrugging his shoulders, and then (partially) sinking, all while having a disappointed look on his face. These sprites are also found in SPSS__.BIN. 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.
SonicCD SpecStage Anim1F 20.png
SonicCD SpecStage Anim23.gif
Animations of Sonic leaping and making a landing. Purpose unknown. These sprites are also found in SPSS__.BIN.
SonicCD SpecStage UnusedJumpFrame.png
A completely unused sprite for Sonic's jumping animation. It has no mappings/animation data attached to it. This sprite is also found in SPSS__.BIN.
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.
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.
SCD fallshrink corrupted.png
SCD fallshrink.png
Corrupted leftovers of an animation of Sonic falling into the distance. Purpose unknown. The only thing that remains are mappings data. Pictured to the right are the missing graphics for said mappings that can be found in the 1996 Windows version.
SonicCD Unused SideRolling corrupted.png
SonicCD Unused SideRolling.png
Corrupted leftovers of an animation of Sonic rolling from an angled perspective. The only thing that remains are mappings data. Pictured at the bottom are the missing graphics for said mappings that can be found in the v0.02 prototype and 1996 Windows version.
Unused sprites of Amy with hearts in her eyes. Not used at any point in the game. In the Sonic CD 2011 remake, these sprites are utilized whenever Amy hugs Sonic.


Art ID Description
SonicCD MCD Sprite Monitors.png
The "S" monitor, with the same icon as in Sonic 1. Breaking this monitor gives Sonic Invincibility, Power Sneakers and a Shield all at the same time.
SonicCD MCD Sprite Monitors.png
A monitor with a blue Ring, which has no effect. In the v0.02 and 510 prototypes, it had the same effect as the "S" monitor, while in the v0.51 and 712 prototypes it acted as an invisible shield that can stack with a regular shield. Its icon would be repurposed for the Combine Ring in Chaotix and the Hyper Ring in Sonic Mania. The flag that gets set when this monitor is destroyed is internally called "conbine_ring", according to the Gems Collection symbol data, so it is possible that the Combine Ring powerup was originally intended for Sonic CD.
SonicCD MCD Sprite Monitors.png
This monitor is supposed to stop time for a few seconds, but it doesn't work correctly. It can stop the animations of Rings and monitors as well as rotating palettes, but that's it.
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 prototypes of Sonic CD, but are unused in the final game. They are non-functional in every known build of the game.
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 sprite present for comparison.
SonicCD MCD Sprite R11A UnusedSplashes.png
04 An unused object in Palmtree Panic that moves downwards quickly for a bit and then disappears, overwriting the level blocks with a singular block as it moves down. Symbol data in the Gems Collection version show that the object was called "taki", which is Japanese for "waterfall". When placed in the Round itself, it uses an incorrect block ID, as seen
. Unused graphics located at 0x03695A in R11A__.MMD (shown to the left) fit the sprite mappings for this object, which makes the object looks like
. This object has existed since the v0.02 prototype.
SonicCD CCZ UnusedSlot.png
An unused object in Collision Chaos that teleports Sonic to a nearby teleporter. Three of these spawn at once and move in a circular pattern. This can be placed with debug mode in the 510 prototype.
SonicCD TTZ UnusedPlatform.png
An unused platform in Tidal Tempest. Found in the Past.
SonicCD TTZ UnusedThinPlatforms.png
An unused thin platform in Tidal Tempest. Found in the Future
SonicCD TTZ UnusedElecBeam.gif
An unused electric beam object in Tidal Tempest. The code for it can be found in the 510 and v0.51 prototypes. Only the v0.51 prototype has working collision detection, where touching it makes it stop.
SonicCD MCD Sprite QQPastPlatform.png
A platform that moves up and down while moving to the left. They come 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). While technically used in the Futures of Quartz Quadrant, these variants for the Present and Past do not appear anywhere in their respective time zones.
SonicCD MCD Sprite QQPastSmallConveyor.gif
SonicCD MCD Sprite QQPastMediumConveyor.gif
SonicCD MCD Sprite QQPastLargeConveyor.gif
Conveyor belt platforms for the Past version of Quartz Quadrant. While these platforms exist in the Present and Futures, they do not appear anywhere in the Past at all, so these Past variants are never seen.
SonicCD MCD Sprite QQPastSwingingConveyor.png
A swinging conveyor belt platform for the Past version of Quartz Quadrant. Like the platforms above, this object exists in the Present and Futures, but this unique Past variant doesn't appear anywhere.
SonicCD SSZ UnusedLightEdge.gif
In prototype builds, in Stardust Speedway, instead of searchlights, it would scroll a lit up palette up and down. These graphics were meant to be placed on the edges of the highlighted area.
SonicCD SSZ UnushedMeshObj.png
Duplicates of the mesh tiles in Stardust Speedway that would be placed as objects.
SonicCD MMZ UnusedTrapDoor.png
An unused trap door object in Metallic Madness. This appeared in prototype builds, but got removed in the final.
SonicCD MCD Sprite SpecialStageItems.png
This appears to be an unused item from the Special Stage. Its use is unknown, but it may have stopped the timer.


Audio ID Description
The time warp sound originally used in the v0.51 and 712 prototypes. Strangely, it is a CD audio track, and can be heard by inserting the game disc into a CD player and playing track #2.
FM NO.21 An unknown harmonica-like sound. FM NO.22 is a duplicate of this sound.
FM NO.26 Sounds like a Spin Dash or a Super Peel-Out being jammed.
FM NO.48 A different version of the sound heard when pressing a button.
FM NO.49 The warning bell usually heard underwater in other Sonic games, only high-pitched. The 2011 rerelease uses this sound, albeit at a lower pitch.
FM NO.50 Sounds like something being shot.
FM NO.54 An electrical sound of sorts.
FM NO.55 A loud, harsh buzzing sound.
FM NO.60 Unknown, but it sounds like something rising or powering up.
FM NO.61 Sounds like FM NO.55, but has a resonating sound underneath it.
FM NO.63 An echo-y spike-like sound.
FM NO.66 A very high-pitched "ding" sound. Later used in Sonic Mania for the Hyper Ring powerup.
FM NO.67 A higher-pitched version of Sonic losing his Rings.
FM NO.68 Sounds like FM NO.63, only without an echo.
FM NO.69 Sounds similar to the door sound at the end of the Metal Sonic race.
FM NO.75 A variant of FM NO.68.
FM NO.76 A variant of FM NO.68.
FM NO.77 A variant of FM NO.68.
FM NO.78 A variant of FM NO.68.
PCM NO.02 A voice clip of Sonic saying "Alright!". According to Masato Nishimura, this may have been intended to play when Sonic passes the signpost at the end of a Zone[3].
PCM NO.05 A voice clip of Sonic saying "Yeah!". This was used as the extra life sound in the v0.51 and 712 prototypes.


Palette Description
A prototype palette that originates as far back as the v0.02 prototype still exists in both acts in the present, with a slightly altered background color, alongside the corresponding palette cycling data.
A prototype palette that was created in between the v0.02 and 510 prototypes still exists in both acts in the past, alongside the corresponding palette cycling data.
Leftover palette data for Sonic 1's title screen, found in every stage file.
Leftover palette data for Sonic 1's level select screen, found in every stage file.

"Comin' Soon" screen

SonicCD510 MCD Comparison CominSoon.png

This screen, which features a scrolling banner saying "COMIN' SOON" while playing the Invincibility theme, was used as far back as the v0.02 prototype when the only two levels in the prototype have been completed, and used for subsequent prototypes after clearing certain Rounds. It manages to survive all the way into the final game and can be viewed by selecting "COMMING" in the stage select.

Special Stage 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 1024 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

SonicCD SpecialStage1 UnusedBGChunk1.png
SonicCD SpecialStage1 UnusedBGChunk2.png

Special Stage 2

SonicCD SpecialStage2 UnusedBGChunk1.png
SonicCD SpecialStage2 UnusedBGChunk2.png

Special Stage 3

SonicCD SpecialStage3 UnusedBGChunk1.png
SonicCD SpecialStage3 UnusedBGChunk2.png

Special Stage 4

SonicCD SpecialStage4 UnusedBGChunk1.png
SonicCD SpecialStage4 UnusedBGChunk2.png
SonicCD SpecialStage4 UnusedBGChunk3.png
SonicCD SpecialStage4 UnusedBGChunk4.png

Special Stage 5

SonicCD SpecialStage5 UnusedBGChunk1.png
SonicCD SpecialStage5 UnusedBGChunk2.png

Special Stage 6

SonicCD SpecialStage6 UnusedBGChunk1.png
SonicCD SpecialStage6 UnusedBGChunk2.png

Special Stage 7

SonicCD SpecialStage7 UnusedBGChunk1.png
SonicCD SpecialStage7 UnusedBGChunk2.png
SonicCD SpecialStage7 UnusedBGChunk3.png
SonicCD SpecialStage7 UnusedBGChunk4.png
SonicCD SpecialStage7 UnusedBGChunk5.png
SonicCD SpecialStage7 UnusedBGChunk6.png


  1. @Mazin__ on Twitter (Wayback Machine: 2019-02-22 19:07)
  2. File:Sonic2 MD JP manual.pdf, page 42
  3. @Mazin__ on Twitter (Wayback Machine: 2021-02-19 15:20)

Sonic the Hedgehog CD
Scd titlescreen.png

Main page (2011)
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Hidden content (2011)
Hacking guide