Ver0.51

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

This prototype is documented on Hidden Palace.

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v0.51 is a mid-development build of Sonic CD, dated June 21, 1993. It was dumped by drx on October 26, 2019 as part of Sonic Month, alongside five other Sonic CD prototypes.

The game has been significantly updated since v0.28a, with all the groundwork laid out and most levels being feature-complete, though there's still a lot of differences.

General Differences#

• A successful time warp counts as a checkpoint; Upon dying in a time period other than the present, you will restart at the position where the warp was activated. This feature was removed after the v0.70 prototype, although curiously, the Japanese manual for the original Mega CD release claims that it exists in the published game. In the manual for the Japanese PC release, the erroneous line was corrected to state that you restart at the beginning of the Zone if you die after a warp.
• The music does not stop when the game is paused.
• The time travel indicator on the HUD is still missing.
• A large amount, if not all, of the PCM sounds are implemented.
• When time traveling, the sound used is a CD audio track instead of an FM sound like in earlier prototypes and the final. Interestingly, this track became unused later in development, still exists in the final build's CD audio tracks, and is labeled as "Metal Sonic" on the OST.
• The badnik teleporter makes no sounds when destroyed.
• Giant Rings make sounds when entering, but they do not animate when you jump into them.
• The Special Stage demo is actually controllable, much like in v0.70 prototype.
• When debug mode is enabled, certain sprites that control Sonic (like in tubes) can be seen if the player gets a shield, invincibility, etc.
• There are various Combine Ring monitors and Clock monitors placed throughout the levels. The Clock monitors work as they did in earlier prototypes, but the Combine Ring monitors have a new functionality - they grant an invisible shield that can be stacked with the normal shield as well.

Graphical Differences#

• Sonic's face on the signpost is the same one from the 510/v0.28a prototypes.
• The drowning numbers from the 510 prototype are now used in-game, and they still use the early graphics that were seen in some prerelease footage of Sonic the Hedgehog.

510-v0.51	v0.70-Final

Audio Differences#

• The noise for defeating enemies is the one from v0.28a and earlier.
• When getting a 1-Up, a different PCM voice sample is played. This voice would later wind up unused in the final build.
• Starting with this build, the music would be compressed to varying degrees. v1.05 build would later add in fadeouts for the compressed CD tracks, and the Special Stage's fadeout would be tweaked by v1.09.
  • Before it was replaced, an early version of the "Speed Up!!" track was compressed. The v0.70 build would replace it with the final version, which in turn would be compressed and equalized in the v1.05 build.

• The unused PCM tracks in the v0.70 prototype exist in the game data, though the "D" variants are simply copies of the "B" variants.
• Most of the Past PCM tracks (with the exception of Quartz Quadrant which reuses Tidal Tempest's) have been implemented by this point. However, a few of them have notable differences.

Palmtree Panic "P" Mix#

• Now matches the final tempo, except for the percussion track which is still the original v0.02 speed. It ends up sounding like 15 beats per measure as consequence, and the music notably pauses a bit at the end of the 15th measure.

Collision Chaos "P" Mix#

To do: There's an extra series of notes halfway into the song.

• Slightly faster. Audio channel and volume mixing is different from the final.

Tidal Tempest "P" Mix#

• Slightly faster.

Title Screen#

v0.51	v0.70

The graphics have been nearly finalized, though the copyright text is thinner compared to later prototypes.

• The Title Screen Cloud Manipulation secret from the final works here, but no ring chime plays (see here).
• To access the level select, press Start on player 1's controller, then B (or C) on player 2's controller.

Stage Differences#

To do: Split these into their own pages, there's enough differences from the v0.70 prototype to warrant it. Actual Layout Comparisons.

Palmtree Panic#

• There is some unusual layout placement next to the giant loop in the beginning of Zone 1.
• There is no robot generator in Zone 2, which makes it impossible to get a Good Future legitimately in Palmtree Panic.
• Zone 3's graphics have been updated at this point.
• The boss in Zone 3 has finalized graphics.
• Flowers are same as final.

Collision Chaos#

• Metal Sonic now has animated sparking sprites when kidnapping Amy.

• Flowers are same as final.
• The rings are green in Zone 1 Present, for some reason.
• The cups can cause the player to lose a life while attempting to time travel.

Tidal Tempest#

• There is an electric beam object that does not exist in the final game. It doesn't hurt you, and touching it will make it stop.

• Flowers are the same graphic as in Prototype 510 & v0.28A, but the single palette is different and accidentally uses a darker shade for what should be the highlights on the stem and leaves.

510 - v0.28A	v0.51	Final

Quartz Quadrant#

• The signs that switch the direction of the conveyor belts don't exist. Instead, there are a few switches placed throughout the stage which change the the direction.
• The conveyor belts don't change their color when their direction is switched.
• You can skip the background changers when respawning at certain checkpoints.
• Bad Future's spin tunnels clip Sonic through walls.
• Flowers resemble Palmtree Panic's, but the petals are hollow and are missing a few pixels.

v0.51	Final

Wacky Workbench#

• Past Zone 1, ring placement ranges from heavily incomplete to completely empty for the rest of the game.
• Flowers are same as final.

Stardust Speedway#

• The Good Future has it's final color palette.
• The object layout for Zone 2 is somewhat incomplete, and there's no rings.
• Zone 3 has an inaccessible area underneath the 3 super ring monitors, which has a super ring monitor, an invincibility monitor, and a speed shoes monitor, most likely to make playtesting easier.

510 - v0.28A	v0.51	Final

• Flowers are the same graphic as 510, however, the palette here doesn't look good either, and looks worse.

Metallic Madness#

• You can skip the Shrinker with precise timing and get stuck at the conveyor section.

510 - v0.28A	v0.51	Final

• Flowers are the same graphic as 510, palette doesn't look too bad except for the leaves.

Special Stage#

This is the first build with playable Special Stages, with a bevy of differences:

• The UFOs are the same ones from some early screenshots, and look nothing like the final game's:

v0.51	Final

• The blue UFO in the final that appears when the player has 20 seconds left does not appear in this prototype.
• The game has a high chance of jumping to a black screen in most emulators if Sonic exits the level or touches the water. Touching the water also produces glitched tiles from the title card rather than the actual water splash graphics.

• If the game doesn't softlock, the results screen will show up with all Time Stones collected, but no score will be given. No music or sound effects play, either. This can frequently happen on real hardware or very accurate Genesis emulators like Blastem. The game also takes you to the next level shortly after this.
• The oil slicks from earlier builds are present, but don't function. The speed boosters don't work, either.
• Sonic controls very differently compared to later builds and the final game: He doesn't run unless the player presses B, and pressing Down will not make him slow down; only letting go of B does.
• Rings and other objects (such as the Power Sneakers) aren't present. The ring counter instead increments every 3 frames.
• There is an unused object that flashes "PRESS START" on screen. It is never spawned, although its graphics are loaded into VRAM.

Watch on YouTube

Maps#

Special Stage 1	Special Stage 2	Special Stage 3	Special Stage 4	Special Stage 5	Special Stage 6	Special Stage 7

Special Stage 1 Stamps	Special Stage 2 Stamps	Special Stage 3 Stamps	Special Stage 4 Stamps	Special Stage 5 Stamps	Special Stage 6 Stamps	Special Stage 7 Stamps

Unused Graphics#

Artwork	Description
	Text that reads "PRESS START", loaded within the Special Stage VRAM.