Sonic the Hedgehog CD (prototype; 1993-07-12)/Hidden content

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Back to: Sonic the Hedgehog CD (prototype; 1993-07-12).

Level select

Scd510 level select.png

On the title screen, press Start on the first controller, then press B on the second controller when NEW GAME or CONTINUE appears. A black screen with a list of numbers and letters corresponding to various levels and events appears just as it looked in earlier prototypes. Make a selection and press Start to enter it. Completing any level or attempting time travel will take the player back to the title screen.

Sound effects test

SonicCD051 MCD SoundEffectsTest.png

On the title screen, press Start on the first controller, then press A on the second controller when NEW GAME or CONTINUE appears. Press C to play the currently selected sound, and Start to exit.

Edit mode


At any time during gameplay, press Start on the second controller to enable/disable edit mode.


  • B: Toggle normal and debug mode.
  • A: Advance forward through the debug object list.
  • Start: Advance backwards through the debug object list.
  • C: Place the selected object at the current coordinates.

Unused content


Audio Description
The time warp sound from earlier prototypes still remains in the game and can be heard under ID SA9 in the sound effects test.

PCM music

Within the ISO image of this prototype are some specific files, preceded with the letters "SNCBNK", with a number and letter afterwards. The numbers refer to the Round 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 a small music clip, played using the PCM chip of the Sega Mega-CD, according to the Round and time zone 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 Sonic CD re-release made one of the fan theories a reality and used most of them to loop the music tracks.

These files are available here (info) (1.97 MB), courtesy of ICEknight. Edited files merged with the CD audio tracks by Shadow Hog are available here (info) (33.56 MB). Discussion of this oddity was held in
Sonic Retro
this forum topic


Sonic the Hedgehog CD (prototype; 1993-07-12), prerelease version of Sonic the Hedgehog CD

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Part of Sonic the Hedgehog CD development