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Proto:Sonic the Hedgehog CD (Sega CD)/Ver0.02

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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.

To do:
Layout differences in Palmtree Panic/Salad Plain, plus any potential unused sprites in the proto.

v0.02 is the earliest known prototype of Sonic CD for the Sega CD. The build is dated December 4th, 1992 (nine months and two days before final), predating the previously discovered 510 prototype, and was created for exhibition at the "Yuusei Sega World" event in Japan that year. It was dumped by drx on October 26th, 2019 as part of Hidden Palace's "Sonic Month."

Much of the game isn't implemented, or is buggy at best. In terms of gameplay, only Acts 1 and 2 of Palmtree Panic are present in the build (though Collision Chaos and Quartz Quadrant do have leftover stage data). This is also the only known prototype that acknowledges the infamous "R2", which is present in the Time Attack screen, and is selectable by using a hex editor but is not functional.

At this stage, the game calls itself CD Sonic the Hedgehog in English; an odd touch considering that the Japanese spelling does put the "CD" at the end of the name. An extra SEGA logo screen is present at the start, complete with classic "Se-ga!" jingle. It was removed after the 512 prototype.

Title Screen

v0.02 - v0.28A Final
Soniccd510titlescreen.png SonicCDJPtitle.png

The title screen has several early elements that would be changed from v0.51 onward:

  • The game's title is CD Sonic the Hedgehog, rather than Sonic the Hedgehog CD.
  • A gold emblem with the Sega logo and the copyright date (1993) is present, but was removed from the final version.
  • The prototype's title screen is 320×224 at 60FPS, but was later changed to 256×224 at 20FPS.
    • All of the perspective effects in Sonic CD are calculated by a co-processor on the Sega CD, which produces tiles that have to be transferred to Genesis VRAM to be displayed. Given that this process has some bandwidth limitations, and that the Special Stage runs at the same resolution and framerate, it is likely that this accounts for the resolution drop in the final's title screen.
  • The clouds are scrolling from left to right, instead of using the sprite scaling layer.
  • Little Planet in the background is more washed out with some dithering.
  • A text string at corner right credits Japanese singer Keiko Utoku of contemporary pop-idol group Mi-Ke for the opening theme song, "Sonic - You Can Do Anything", for press purposes. The song itself also plays here, instead of the opening cutscene.

Salad Plain (Palmtree Panic)

Palmtree Panic was originally called Salad Plain, according to the Time Attack screen (see next section below).

Past Present Bad Future
CDSONIC0.02-SP1B.png CDSONIC0.02-SP1A.png CDSONIC0.02-SP2D.png
  • The color palette has slight differences, and the palette data and palette cycling data are still in the final game.
  • It's not possible to get a Good Future in this build. However, the level files for Good Future are present.
  • To access the Good Future variants of the levels, change bytes at 0xA1A in the Track 1 binary to 0070 for Zone 1, and 0058 for Zone 2.
  • The Good Future variants use the music for the Past variants, despite the track for Palmtree Panic's Good Future existing in the build.
  • The Present has a different background, notably shorter and less geometric mountains. This early background is the basis for the other time zones' backgrounds, which were unchanged in the final game.
  • The palm trees have a more asymmetrical design.
  • Amy is nowhere to be found in the present version of Salad Plain Zone 1.
  • The big loop at the beginning of the present version of Salad Plain Zone 1 is missing. In its place is a small ramp and a spring.
  • Breakable parts of the walls have not been added to the levels yet.
  • The yellow spring that bounces Sonic away from the goal is missing.


You don't make friends with salad, Sega figured.
  • The graphics are extremely basic.
  • Only Palmtree Panic Zones 1/2 are normally selectable, and is referred to as "Salad Plain." Although by hex editing values on the Time Attack menu, it is possible to bypass the restrictions of being stuck with R1-1 and R1-2 and you can select other levels, although there are no other Zone previews on the left when going beyond Salad Plain. Most levels unfortunately lead to a black screen (including R2) however R3-2 and R5-1 still have existent level data leftover in the prototype and you will be taken to a broken Salad Plain Zone level upon selecting either one. R7-3 strangely, takes you to an unused level select that's seen in later prototypes instead of black screening. The unused level select itself is barebones and selecting anything but the first option will take you back to the Time Attack menu.
  • This is the only prototype that explicitly references the scrapped "R2" as a level entry in the Time Attack menu, without having to hack the game to access the level select. All other known versions of the game jump from R1 (Palmtree Panic) directly to R3 (Collision Chaos). It is unknown why R2 was cut, though Jim Trethewey, who helped develop the Windows port, said in an interview that Junetsu Kakuta (who worked on the game) implied the level was removed due to quality and design concerns.
  • Collision Chaos' Present theme is used here instead of the actual Time Attack music.


  • Some of Sonic's animation frames are buggy. His "Peel-Out" animation isn't implemented.
v0.02 510 - Final
Note: The last sprite in the animation has part of it cut-off in-game. SCDImOuttaHereFinal.gif
  • The sprites for the "I'm outta here!" animation are quite different, with dimmer shading in certain frames as well as different posing for Sonic as he leaps off.
Sonic 1 v0.02 510 - Final
Sonic1 Spring.png SonicCD 0.02 Spring.png SonicCD Spring Final.gif
  • Sonic still has his spring frame from the original Sonic the Hedgehog, but it's not exactly the same - his shoes were redrawn to add the white stripe. The spinning animation also exists in this prototype, and is used during the time travel sequence.
  • The lives counter is placed slightly higher than normal, and there are no zeroes in the "SCORE" and "RINGS" counters. The RINGS counter does not flash red when the player has zero rings.
  • Active time warps are not yet indicated on the HUD.
v0.02 510 - v0.51 712 - Final
Soniccd 0.02 yousay.png
  • The goal post reads "You Say!", an apparent pun on "Yuusei," the name of the event where this build was featured[1], and does not spin when the player passes it. This also appears in the earliest screenshots available of the game.
  • The graphics for Palmtree Panic are more uniform, with less distinctions among the time zones.
  • The Time Attack mode looks nothing like the final, and features the early name for Palmtree Panic.
  • The time travel graphic is extremely basic, featuring only blue lines on a white background.


v0.02 Final
v0.02 v0.70 - Final
  • Palmtree Panic's Past theme is stored as CD audio, while in the final it was remade into sequenced PCM audio. It also uses a different mix.

The choice for the Past themes later using sequenced PCM audio is for space-related reasons; the CDDA version of the songs "just wouldn't fit" compared to the PCM ones.

(Source: Mazin on Twitter)

When accounting for four CD audio variations instead of three (for reference, an average Sonic CD track is 1-2 minutes, or 10-20 megabytes), the data and music stored on the Sonic CD disc amounts to 600 - 700 megabytes which is dangerously close to an audio CD's storage capacity limit (around 650 - 700MB).

v0.02 - v0.28A Final
  • The time warp sound is different, and very grating on the ears. This would be changed in v0.51, and again for v1.05.

Gameplay Differences

"I'm outta here!"


The "I'm outta here!" trick (where Sonic jumps off the level after three minutes of no controller input) doesn't work the same as it does in the final version of the game: the camera tracks Sonic as he falls, and he dies when he reaches the bottom of the level instead of just disappearing and triggering a Game Over. Plus, after respawning, Sonic retains any rings previously collected.

Time Traveling


Time traveling doesn't seem to work correctly, as using the spinners will instead cause the current level to restart rather than letting Sonic warp through time (the time warp appears short here because the black screens were trimmed out of the GIF).

Physics Oddities


Sonic the Hedgehog's programming was used as the basis for Sonic CD, but at this point the physics weren't fully optimized for this game, resulting in several oddities:

  • In Salad Plain Bad Future, colliding with solid collision tiles whilst standing on the collapsing diamond platforms can cause glitches like the infamous "slope zip" glitch.
  • Charging a Peel-Out for about 21 seconds warps Sonic near the end of the act. Charging it several seconds longer will crash the game.
  • Running fast or charging a Spin Dash or Peel-Out does not cause the camera to move.
  • Sonic takes a lot longer to charge a Super Peel-Out. The maximum speed it gives is also limited by Sonic the Hedgehog's speed cap.


  • The game cannot be paused.
  • Two additional item monitors are present in this build.
    • Blue Ring: When broken, Sonic will run faster and be granted temporary invincibility. In later builds it acts like a triple-layered shield (as-in, it gives three additional hits), but was later removed from levels.
    • Clock: Meant to freeze time for a few seconds, but is incomplete, as it only freezes the animation of objects other than Sonic.
  • Pressing Start on the second controller spawns a second Sonic. That player will then able to control that Sonic.
  • Collecting 50 rings does not spawn a Special Stage ring at the end of a level.
  • The player can not change the direction while roll-jumping, like in the other Mega Drive / Sega Genesis Sonic games.
  • If the player loses all their lives or beats Salad Plain Zone 2, a "COMIN' SOON" screen will appear, after which the game resets. This screen actually made it into the final game, and can be viewed using the level select.
    • The Palmtree Panic Good Future theme plays on this screen instead of the invincibility theme used in later builds, likely because the latter track wasn't finished yet.
v0.02 510 - 712
SonicCD v0.02 Level Select.png SCD510 levelselect.png
  • The level select screen is present in the files, and can be accessed through modding. Change bytes at 0xA1A in the Track 1 binary to 011A.
    • Only up to "COMMING" is accounted for. It is also instead marked as "COMMING SOON".
    • Oddly, selecting anything other than "1-1-A" will send the player to the Time-Attack menu.

Unused Objects

To do:
Add documentation of the leftover glass bumper object of Collision Chaos seen here.

Object 27

This appears to be an unfinished tilting platform object. Its graphics get loaded at certain points in the stage, usually around the small logs. It was scrapped by the time of the 510 prototype.

Object 29

This is likely a preliminary swinging platform object for Tidal Tempest. Interestingly, if spawned with the subtype "00" in the game, it underflows and tries to spawn 255 sections of the "chain," causing immense load times and lag.

Object 04

This object does exist in later prototypes and in the final game. It seems it was meant to be an object that would overwrite tiles, likely trying to create a "flowing waterfall" effect. It seems it didn't get very far in development.

Object 08

Easily the most interesting unused object in this prototype. It appears to change level layout when Sonic touches it. Nothing like this exists in later prototypes or in the final game.

(Source: Nat the Porcupine)

Unused Sprites

To do:
Sonic has a ton of animations that aren't used here but are in the final, as well as some straight-up unused ones. Document them, and see if there are any other unused sprites.
Artwork Description
SonictH1 Gen Dead Sprite.png
A black-and-white death sprite, whose purpose is unknown. This is also present (and unused) in the original Sonic the Hedgehog, and the 1996 Windows version.
SonicCD Unused SideRolling.png
Two different angles of Sonic rolling, intended for the 3D loop in Palmtree Panic 1. These sprites are also present (unused) in the 1996 Windows version.
SCD 002 FrontRoll.png
More angled sprites of Sonic rolling. These are used in the Final version on the 3D loop.
SonicCD 002 UpBack.png
A sprite of Sonic looking over his shoulder. This is also in the final game, unused. A black pixel was removed between his legs in the final version.
SonicCD Sneeze.gif
An animation of Sonic sneezing. It's also unused in the final version.
An animation of Sonic waving his arms around while walking. This is also unused in the final.
SCD 002 Hang.png
An animation of Sonic hanging onto something. These sprites are also unused in the final, but a different animation is used where his feet hang down instead. His shoes were made less pointy in the final version.
SCD 002 Flume.png
A secondary hurt sprite, grabbed from Sonic 1. Used in the final version.
SCD 002 Air.png
A sprite of Sonic grabbing an air bubble, grabbed from Sonic 1. Used in the final version.
SCD 002 Spin.png
A sprite of Sonic spinning around, grabbed from Sonic 1. Used in the final version.
SCD 002 Drown.png
A sprite of Sonic drowning, grabbed from Sonic 1. Used in the final version.
SCD 002 Pole.png
A sprite of Sonic hanging onto a pole, grabbed from Sonic 1. Used in the final version.
SCD 002 MiniSonic.png
An entire sprite set for Sonic's mini form. Appears incomplete. There is unused code that calls these sprites.
SonicCD002-Unused Disc Statue.png
This is an object that exists in the debug list - however, placing it does nothing. The graphics for it do exist in the data, and it seems to be a log bridge and post, similar to those found in other Sonic games.

Unused Sound

To do:
Check if it's exactly the same as the final version.
  • In the data of the opening FMV, there's some music data containing "Sonic - You Can Do Anything". It is the same as the one played in the final version (which includes the re-recorded vocals).

Mini Sonic

Setting RAM value FFF75E to 01 will activate Sonic's mini form, used in the final's Metallic Madness.

Leftovers from Other Zones

Collision Chaos

There is leftover code that handles the bumpers and glass orbs in Collision Chaos Zone (R3). It specifically checks for that zone ID, so overriding it will activate the function. The function itself is nearly identical to the final's, and even uses the same block IDs for checking bumpers with. There's also code that checks for the pinball flippers in Sonic's object code. It also has its own entry in the level events routine for updating the camera boundaries.

Tidal Tempest

The function for handling loops and spin tunnels has a check for Tidal Tempest's zone ID, and activates the function for that zone. The graphics for the fish can also be found in R11A at location 0x3457A.