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Proto:Sonic the Hedgehog CD (Sega CD)/Prototype 712

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

Hiddenpalace.org logo.png  This prototype is documented on Hidden Palace.


Prototype 712 is a much later prototype of Sonic CD, named because the CD dates itself to July 12th, 1993. This is a later build of the game that is near completion, but is still unfinished in places and has some differences. One version was found and dumped by Phugolz, while a second one was found and dumped by The Cutting Room Floor and Hidden Palace on October 26th, 2019, as part of Sonic Month.



  • Despite the Title Screen having the proper title, the game is still referred as "CD SONIC THE HEDGEHOG" internally.
  • Save files created by this prototype can be used in the final game, and vice versa.
  • Debug mode can be used in Time Attack. It was disabled in the final to prevent cheating.
  • The robot transporter in the Present doesn't appear to have degraded as much as it has in the final.
  • Invisible objects that catapult Sonic into ball form (usually found in tubes) will become visible with shield, invincibility or time warp graphics if Sonic has any of those items in effect.
  • The "S" and Clock monitors have been removed aside from a secret room in Palmtree Panic 3, but the Blue Ring monitor can still be found in a few sporadic locations throughout the game. They also have their effects changed somewhat:
    • The "S" monitor, when placed with Debug Mode, not only grants invincibility and power sneakers, it also gives you a shield.
    • The Clock monitor, when placed with Debug Mode, causes other monitors to stop blinking.
    • The Blue Ring monitor now functions like an invisible shield, allowing you to take a hit without losing your rings. It can also stack with a regular shield.
  • Getting all the Time Stones doesn't automatically destroy all robot transporters and thus won't change all futures to Good Futures.
  • The game-ending "I'm outta here!" easter egg now causes an instant Game Over as intended, but the camera will still follow Sonic as he jumps off the stage, dying from reaching the bottom of the stage.
  • The player will always get a bad ending even if the the player has destroyed every robot transporter in the game or collected all the Time Stones. The good ending has been implemented though, and can be viewed in Visual Mode.
  • The ending FMVs have no music or sound effects, and don't display the "TRY AGAIN/YOU'RE TOO COOL!" messages or the "Presented by SEGA" text at the end.


  • The jump sound doesn't work properly in normal stages. It works in the Special Stage, though.
  • The Super Peel-Out doesn't play any sound effects, but the Spin Dash does.
  • Destroying a badnik plays a different sound rather than the traditional badnik explosion sound.
  • When you gain an extra life, instead of Sonic saying "Yes!", he says "Yeah!".
  • Destroying the robot transporter in the Past doesn't play a sound after the explosion.
  • The goal sign doesn't make a sound when passing it.
  • Pausing the game does not pause the music; it simply mutes it.
  • The time warp sound is different from both the 510 prototype and the final, this time playing a CD audio track that would go unused in the final. It is track #33, whereas it would be track #2 in the final. It is still present in the Windows release where it is dubbed as "Metal Sonic" by CD readers and iTunes:
Prototype 510 Prototype 712 Final
  • The title screen music is the same on from 510.

Special Stage

Notice the different starting position.
  • Much like the prototype before it, the Special Stage demo that plays by waiting at the Title Screen isn't a demo at all; it is fully controllable.
  • The starting points for all Special Stages are in odd places, such as on the far corner on the dirt that slows you down or partially inside a bumper, instead of starting on the road.
  • Sonic doesn't strike a pose when the Special Stage begins.
  • The oil slicks are present but don't affect game play in the Special Stage.
  • When a UFO is destroyed, the UFO counter doesn't count down until the UFO stops exploding. In the final, it counts down immediately after smashing the UFO.
  • When all UFOs are destroyed, the Time Stone doesn't wait until the camera finishes turning around Sonic and drops as the camera starts turning. It also doesn't make a sound.


  • Menu navigation on the title screen is inverted.
  • The preview for Special Stage 6 in the Time Attack menu doesn't animate.
  • The RAM Data screen has very different visuals:
Prototype 712 Final
Soniccdramsavescreen712proto.png Soniccdramsavescreenfinal.png
  • The RAM Data menu is not fully functional and has some bugs that would be fixed in the final:
    • You cannot copy your save file to the Sega CD's internal RAM if a RAM cartridge is not present or there isn't already a Sonic CD save file copy in the internal RAM.
    • Erasing your save file doesn't appear to work.
    • You can't seem to replace your save file with one saved in storage.
  • The D.A. Garden is called "Sound Test" on the title screen.
  • Exiting the D.A. Garden will lock up the game.
  • The Visual Mode screen does not have background music.
  • "Opening" is misspelled as "Openning" on the Visual Mode screen.
  • The pencil test hasn't been implemented and cannot be viewed yet. Selecting it in the Visual Mode will just play the opening FMV.

Cheat Codes

The level select screen in this prototype is the same as in the 510 prototype.

Level Select

On the title screen, press Start on the first controller and then press B on the second controller. A black screen with a list of numbers and letters corresponding to various levels and events appears just as it looked in the 510 prototype. Make a selection and press Start to enter it.

Note that you will be taken back to the title screen upon completion of the selected level or upon attempting time travel.

Sound Effects Test

On the title screen, press Start on the first controller and then press A on the second controller. A black screen with a list of hex numbers preceded by the letter S appears. Press C to play the selected sound, and press Start when you want to return to the title screen.

Debug Mode

Press Start on the second controller at any time during gameplay to enable/disable Debug Mode.


Palmtree Panic

  • There is no rock at the end of Act 2 to stop you in your tracks.

Collision Chaos

  • The background parallax in the Past glitches out at the top of the stage near the end of each Act.
  • The mini bumpers that surround the yellow point cups make the same sound as the large bumpers when collided with.
  • PCM-based sound effects such as the bumpers don't work in Act 3.

Quartz Quadrant

  • The outdoor background in the Good Future is still different. The sky is black, the mountains are darker, and the foliage is less refined.
  • The end of the upward transport tube near the robot transporter in Act 2 has a group of large platforms at the end, stopping you from flying right into the transporter. They were removed in the final.

Wacky Workbench

SonicCD712 WackyWorkbench.png
  • The bouncy floor doesn't make any sounds.
  • The angel statue in the Past of Act 1 is a solid object and doesn't give you rings.
  • Act 3 has an arrangement of rings before the boss that spell out "CD". This arrangement is replaced with a pyramid of rings in the final.
  • The capsule at the end of Act 3 is sunken into the floor a bit.

Stardust Speedway

  • Parts of the foreground in the Past are blue instead of yellow.
  • The sky in the Bad Future is constantly flashing red.
  • There is no spring in the way of the goal in Act 2.
  • The boss music doesn't start during the intro to the Metal Sonic race. It instead begins when the race starts and plays throughout.
  • The background parallax in the Good Future of Act 3 glitches out near the end of the race.

Metallic Madness

SonicCD712 MetallicMadness.png
  • Trapdoors similar to the ones in Scrap Brain Zone from Sonic 1 can be found. These remain from the 510 prototype, and can also be seen in a screenshot on page 49 of the European manual.
  • The area where the robot transporter is in the Past of Act 1 has more springs than spikes.
  • The shrink laser has a delay before firing each laser instead of firing constantly. The growth laser, on the other hand, is constantly firing like in the final.
  • The door to the goal in Act 2 is guarded by three Big Bombs in all timezones.
  • The whole stage doesn't explode when the final boss is defeated, and Amy doesn't appear.

Unused PCM Music

Buried within this prototype are some specific files, whose filenames are preceded with the letters "SNCBNK" with a number and a letter afterwards. The numbers refer to the zone and the letters refer to the time period for which the file represented. For example, "SNCBNK1A" represents Palmtree Panic in the Present.

Each file is played using the PCM chip of the Sega CD according to the zone and timezone it represents. Files that end with a "B" are the full music tracks for the Past stages and would remain in the final, while the rest are all small music pieces that are not used and would be removed in later builds and the final.

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 inevitable gap created when a looping CD audio track rewinds to start again.
  • They were intended to be played at the start of a level, before the CD audio played.

The 2011 rerelease of Sonic CD, developed partly by people who used to frequent the online Sonic communities, made one of the fan theories a reality and used most of these to loop the music tracks.

Fileame Sound Corresponding Zone
Palmtree Panic Present
Palmtree Panic Good Future
Palmtree Panic Bad Future
Collision Chaos Present
Collision Chaos Good Future
Collision Chaos Bad Future
Tidal Tempest Present
Tidal Tempest Good Future
Tidal Tempest Bad Future
Quartz Quadrant Present
Quartz Quadrant Good Future
Quartz Quadrant Bad Future
Wacky Workbench Present
Wacky Workbench Good Future
Wacky Workbench Bad Future
Stardust Speedway Present
Stardust Speedway Good Future
Stardust Speedway Bad Future
Metallic Madness Present
Metallic Madness Good Future
Metallic Madness Bad Future
Final Fever
(Source: Sonic Database, ICEknight, Sonic Retro)