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Proto:Sonic the Hedgehog (Genesis)

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This page details one or more prototype versions of Sonic the Hedgehog (Genesis).

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

Sonic1proto titlescreen.png

A prototype of Sonic the Hedgehog was released by Hidden Palace at midnight (GMT) on January 1, 2021. It depicts the game midway through development. Many stages cannot be completed due to the lack of signposts and bosses; some (like Clock Work Zone Act 3 and Final Zone) haven't been started at all, or are obvious placeholder designs (like the Special Stage).

This build reveals a game that was originally tuned more for traditional platforming and exploration rather than for speed, which eventually become the hallmark of the Sonic series. It also features a plethora of interesting later-cut contents that was previously only seen in grainy magazine screenshots and raw gameplay footages, like the rolling checkered boulder in Green Hill Zone, the UFOs in Marble Zone, and Spring Yard Zone when it was still called Sparkling Zone. Also, Splats the Bunny!

Long considered a holy grail by the Sonic community, a Sonic 1 prototype was sought after for around two decades. During the time before this build surfaced, prototypes of all the other 16-bit Sonic games had already been discovered, dumped and shared with the public. Along the way, there were also a few ROM hacks created, as attempted guesses to what such a prototype would look and play like (including Sonic 1 Beta Hoax, and Sonic 1 Beta Remake).

It wasn't until late 2020 that an individual by the name of Buckaroo found a cartridge containing this prototype, and released its contents through Hidden Palace (on New Year's Day) for gamers to enjoy. According to drx, this build was originally sent to an unspecified UK video game magazine in early 1991 for their pre-release coverage.

Download.png Download Sonic the Hedgehog (Genesis Prototype)
File: Sonic_the_Hedgehog_(16-bit)_(Prototype).bin (512 KB) (info)


Hmmm...
To do:
Stuff to add that's not accessible in the base ROM without patches. Some of this might be in patches that are available on release:
  • Changed chunks
  • There's a lot of minor changes that one normally wouldn't notice (e.g. Sonic has no ceiling collision when hurt). There's also unused content from earlier builds that hasn't been removed yet.
  • This disassembly should help out a lot.

Zone Differences

Normally, only eight stages are playable without the Level Select. In order: Green Hill Acts 1-3, Marble Acts 1-3, Sparkling Act 1, and Star Light Act 1. This disproves the long-held theory, based on the level select of the original "REV00" US release (which also happens to match this build, different Zone names notwithstanding), that the level order was rearranged late in development.

Final Zone isn't available in the Level Select, and levels use their early names. Every Zone contains many differences in the layouts themselves.

Zone ID 06, which is used in the final game for the ending, hasn't been implemented yet. Trying to access it by modifying the current Zone/Act address will lead to "ZONE ACT. 1" briefly appearing onscreen, followed by the game softlocking because no level data exists for this level slot.

However, the "Act 4" stage ID (03) is also functioning, to varying degrees. Most other levels either contain nothing or an object layout from the first Act of that stage. Notably, Green Hill's "Act 4" slot contains a complete duplicate of Act 3, heavily implying it was once considered for the ending cutscene before being moved to its own level slot.


Sonic1ProtoGHZThumbnail.png
Green Hill Zone
You can't stop the Rock.
Sonic1ProtoMZThumbnail.gif
Marble Zone
UFOs are real.
Sonic1ProtoSZThumbnail.png
Sparkling Zone
Good luck.
Sonic1ProtoLZThumbnail.png
Labyrinth Zone
Thankfully, there's no water here.
Sonic1ProtoSLZThumbnail.gif
Star Light Zone
Under heavy construction.
Sonic1ProtoCWZThumbnail.png
Clock Work Zone
Before the big Scrap.

Special Stage

S1ProtoSS Full.gif

There's only one Special Stage in this build, with a very simple and unexciting layout, implying that it was only a temporary design.

  • Only C can be used to jump. A and B respectively speed up/slow down the stage's rotation counterclockwise and clockwise, and pausing the game will reset the rotation speed. There's no upper cap on the rotation speed, meaning it's possible to hold A or B for long enough to overflow it and have the stage start rotating in the other direction. It's stored as two bytes in address F782 in 68K RAM.
  • Only two bumpers are in the entire stage.
  • A few clusters of rings are present near the start point, but that's all until the player gets to the "Emerald."
  • Instead of a Chaos Emerald to collect, an ordinary green block is used as a placeholder, which does nothing when touched.
  • Goal tiles are split in two: the blue ones (with "GOAL" on them) don't animate or function, but their second frame (red tiles) will spin the stage around rapidly like normal before pausing for a moment, then resetting the stage.
  • The player cannot enter object placement mode, despite debug mode being enabled by default in this prototype, and thus cannot move freely around or place objects of any kind.
  • The UP and DOWN tiles - just one of each present in the whole stage - don't animate either, and seem to function like Reverse blocks instead of adjusting the rotation speed.
  • Collision detection seems to be less refined, with Sonic being able to stick to tiles much easier than in the final game.
  • No score summary is displayed upon exiting the stage.
  • The screen doesn't fade to white when entering or exiting the Special Stage.
Sonic1ProtoSSTransition.gif

If the Special Stage layout is edited to remove objects, the player can go out of bounds. Notably, the out-of-bounds garbage data differs from not only the final's out-of-bounds area but also this prerelease screenshot that also looks very much out-of-bounds. It is also extremely prone to crashing often.

  • Only the colored blocks, bumpers, and Goal spheres can be seen in the garbage data.
  • Attempting to go further down into the garbage data will cause the graphics to deform and the collision to become glitchy to the point where Sonic can't go further down.
  • Going left or right will also cause the graphics to deform, but the player can continue going left or right until the strip of garbage data loops.

General Differences

ROM Header

The prototype doesn't yet have its own ROM header and instead contains basic template information, with the name just being Genesis and having a date stamp of 1989.JAN, implying that this build was somehow compiled before development had even begun. A reasonable estimation, based on visual cross-checking against UK prerelease coverage of Sonic, places this prototype around February/March 1991.

Pre-game Content

Proto Final
Just your typical average Sega Logo, nothing too special here. SEGA!

Instead of the well-known "Sega!" logo and iconic chant, this prototype uses the standard (and silent) palette-cycling Sega logo which opens most other Genesis/Mega Drive games. Unlike in the final game, the logo can be skipped at any point with the Start button.

The title screen immediately follows; there is no SONIC TEAM PRESENTS card. (At the time, Sega did not normally credit their internal development teams within games.) Unfortunately, adding this screen also created a minor bug. More on that below.

Proto Final
"PRESS START BUTTON" What button starts the game?

The prototype's title screen lacks the ™ symbol (not unlike the Japanese release), and features a flashing PRESS START BUTTON graphic that's absent from the final. It's still present in the game, but due to a buggy implementation of the SONIC TEAM PRESENTS card, it never appears onscreen.

During attract mode, BGM doesn't immediately stop when the Sega logo is displayed; the music fades out slowly instead.

Early Demos

Green Hill Zone Marble Zone Sparkling Zone
Special Stage Star Light Zone (Unused)

While the demo cycle only shows Acts 1 of Green Hill Zone, Marble Zone, and Sparkling Zone, a demo of Star Light Zone Act 1 is present. It's not normally seen due to the demo cycle having a total of 12 entries, but the demo player code forcing a loop after the sixth. The Special Stage demo also plays in between every stage, rather than being played only at the end of the demo order in the final release. There are no demos present for Labyrinth Zone nor Clock Work Zone.

At first glance, the demos would appear to be broken, as Sonic dies almost immediately by running into enemies or falling off the level. In Marble 1's case, this is because it belongs to an earlier layout in which Yadrins weren't present yet. Green Hill 1's demo is broken because, oddly enough, it's assigned to the wrong level, and actually belongs to this same early level layout for Marble 1. Similarly, Star Light 1's inputs are meant for an earlier Green Hill 1. Why these demos are assigned to the wrong level is anyone's guess.

It's currently unknown what stage the inputs used in Sparkling 1 were meant to be used for, but by restoring an leftover object layout for the stage, it appears to result in a working (though not perfect) demo. Whether this is just coincidental or if that is the layout the demo recording was intended for is currently unknown.

Green Hill with correct inputs Marble Zone with correct inputs
Sparkling Zone with correct inputs(?) Special Stage but edited to make the demo sync

The demo order in code is as follows (entries marked in bold are normally unseen):

  • Green Hill 1
  • Special Stage
  • Marble 1
  • Special Stage
  • Sparkling 1
  • Special Stage
  • Star Light 1
  • Special Stage
  • Marble 1
  • Special Stage
  • Sparkling 1
  • Special Stage
Proto Final
Uh-uh Finally no Xs

Level Select and Debug Mode are enabled automatically in this build for testing and preview purposes.

  • In debug, holding A and pressing C won't yet go backward in the object list, and instead places the highlighted object regardless.
  • The game acknowledges the B button as a jump input before activating debug mode with the same button. This causes Sonic to jump on the frame before entering debug mode, and performing said jump after exiting debug mode. This was fixed for the final version.
  • Spring Yard and Scrap Brain were called Sparkling and Clock Work in this build.
  • The level select contains Xs next to Star Light Zone and Clock Work Zone Act 3. These were likely used for when a stage hasn't been implemented yet (though in this build it's a bit outdated, since Star Light Zone has been implemented).
    • Clock Work Act 3 cannot be selected.
  • Pressing B on the Level Select will load up Act "4" of Green Hill Zone (displayed on the title card by a copy of the blue oval graphic replacing the Act number), which suggests that it might have been used to test the ending sequence stage. In the final game, the ending stage instead uses a separate Zone altogether (06).

Gameplay

HUD Differences

Proto Final
Sonic1ProtoGHZ-1.png Sonic1FinalGHZ-1.png
  • As seen in countless prerelease screenshots, the HUD says "RING" instead of "RINGS". The change was made circa the build seen in Shinsaku Soft Video, rather close to the end of development.
    • "RING" does not flash red when the player has 0 rings, nor does "TIME" flash when the clock reaches 9:00.
    • "TIME OVER" does not occur when the timer reaches ten minutes. The timer instead loops back to 9:00 indefinitely.
    • The time bonus works differently.
    • During a Game Over, the timer will continue counting up. The final game stops the timer.

Sonic

  • Sonic's jump height is lower. On flat ground, the apex of his jump is 6 pixels lower than in the final.
  • Sonic's collision height doesn't change when crouching.
  • Sonic's deceleration speed is slower, being $40 in the prototype and $80 in the final. The Power Sneakers deceleration speed is $80 in both this prototype and the final game, as it was not adjusted to account for the regular deceleration speed change, resulting in the Power Sneakers deceleration speed and regular deceleration speed being identical in the final.
  • Walking/jumping onto objects such as platforms and bridges causes Sonic to lose some of his speed.
  • When hurt, Sonic has no collision with ceilings.
  • Sonic doesn't automatically run off the screen after touching the end-of-level signpost and destroying the post-boss Animal Capsule, nor is the player capable of doing so yet. Jumping during the ensuing end-of-level bonus tally causes Sonic to enter the "victory fist pump" pose seen in many prerelease screenshots.

Objects

Hmmm...
To do:
Perhaps a comparison video between the proto and final Special Stage ring animations should be added.
  • The hidden end-of-Act bonus point markers haven't been implemented yet.
  • Special Stage rings haven't been added to the end of Acts 1 and 2 yet. The ring object does exist with full graphics and coding, though it works completely differently from the final game:
    • When Sonic touches the giant ring, instead of instantly disappearing like in the retail version, he instead momentarily gains a "sparkle" effect, after which he then "warps" off of the screen (similarly to the way time travel works in Sonic CD). However, there doesn't seem to be any further coding for it beyond this point in development, as Sonic simply reappears a short distance ahead of the point where he vanished a brief moment after he disappears.
    • Given this behavior, it's probable that the Special Stage rings were originally intended to be placed at ground level just past the signpost instead of up in the air, to give the illusion of Sonic running through the ring and then warping away to the Special Stage. Why this was altered is unknown, but given that remnants of this functionality still exist in the final ROM, it's likely that it was changed fairly late in development.
  • Checkpoints are completely absent. In fact, they haven't been coded into the game at all at this point.
Sonic1ProtoInvincibilityBug.gif
  • Spikes damage Sonic during all forms of invincibility, including from monitors.

Screens

  • The Continue screen hasn't been implemented yet, likely because there's no normal way to earn Continues in this build.
  • The ending cutscenes and credits are completely absent.

Scrolling System

  • Vertical positioning is somewhat buggy:
    • The camera is much slower when moving vertically, making it easier to outrun the camera (and, in some rare cases, die when doing so) when falling or traveling at high speeds.
    • The top and bottom of the stage wrap in every level, even in stages that don't normally utilize vertical wrapping. In stages with lethal pits, this results in the player dying if they travel above the upper stage limit (since Sonic wraps from the top to the bottom of the stage, where the game then thinks he's fallen into a pit).
Sonic1ProtoSlowVerticalSpeedBug.gif

Debug Mode

Proto Final
Sonic1ProtoCamBounds.png Sonic1FinalCamBounds.png
  • Object placement mode ignores camera boundaries. Camera movement also works differently, meaning going to the same coordinates in the same way won't always result in the camera being positioned the same way.

Misc.

Proto Final
Sonic1ProtoMZ3Transition.PNG Sonic1FinalMZ3Transition.PNG
  • When a Zone is completed, graphics for the next Zone start decompressing during the fade-out, before the Act transition completes.
  • Collision is noticeably glitchy, especially when rounding a small incline.
  • There is no combo bonus for destroying multiple Badniks in a row yet.
  • Onscreen enemies are not cleared after finishing an Act, and can still harm Sonic while the player's score is being tallied. (This can be easily observed in GHZ Act 1.)
  • Extra lives are earned at 50 and 100 rings, instead of 100 and 200 in the final release.
    • "Ring memory" doesn't exist yet, meaning it's possible to earn two 1-Ups by collecting 100 rings, take damage, and then earn another two 1-Ups by collecting 100 more rings. In the final release, each ring threshold only grants one 1-Up per life, per level.
  • BGM and sounds continue while the game is paused.

Graphical Differences

Proto Final
GREEN HILL ZONE ACT. 1 GREEN HILL ZONE ACT 1
  • Title cards have an additional period after "ACT". This was removed from the final, although the period remains in the data.
  • Sonic's sprites are almost identical to the final game, but he lacks his updated "breathing" animation and his extra hurt sprite (used for slides).

Unused Content

Unused Sprites

Sprite Location Notes
Sonic 1 Prototype Font.png
$018000 An 8×8 font with 3 copies in different colors. The palette used in this image is a mockup.
Proto Sonic The Hedgehog Genesis smoke puff.png
$02656E Some dust or puffs of smoke. These are also unused in the final game, but are noteworthy in this prototype for being loaded in VRAM where the checkpoint graphics are in the final version.
Sonic 1 Prototype Water Splash.png
$026672 The Labyrinth Zone water splash, not used in this prototype as there is no water. It has simpler shading and seems to be intended to use Sonic's palette, unlike the final game which uses Labyrinth's cycling palette. It should be noted that these sprites do appear to be re-used in Sonic CD.
Sonic 1 Prototype Sparkle.png
$0267D4 Some sparkles.
Sonic1Proto MD Sprite UnusedFlame.png
$026BF6 Some fireballs, possibly for use in Marble Zone.
Proto Sonic The Hedgehog Genesis early Ballhog.png
$02A386 Ball Hog is completely programmed in the prototype, but its movement, sprites, and attack are different from the final version: It walks from side to side and drops bombs down vertically. This seems to match the version seen in early prerelease footage, rather than the version seen in leaked Digitizer artwork from the game's development.
Sonic1ProtoMDBallHogBall.png
$02BBC2 The Ball Hog's ball is also programmed in the prototype, meant to explode when it first hits the ground, unlike the final which bounces for a bit and then explodes.
Sonic 1 prototype Boss Spring.png
$060864 A spring included in the boss attachments art file. The base of the spring was recycled for the Marble Zone boss's fire disposer. Given that the boss attachments tend to follow the gimmicks of their Zone, this was probably intended for the Sparkling/Spring Yard Zone boss.
Proto Sonic The Hedgehog Genesis R icon.png
$06505E An R Block meant for the Special Stage. Doesn't load in the Special Stage. Its intended use was probably the same as final, although no code for it appears anywhere.
Proto Sonic The Hedgehog Genesis Skull icon.png
$06512E A skull meant for the Special Stage. Use unknown, though it probably had something to do with either death or losing.
Proto Sonic The Hedgehog Genesis U icon.png
$0651FE What appears to be a magnet icon meant for the Special Stage. While it's unknown what the purpose of it is, it's suggested that it could be used for two possibilities: it could be an item to allow Sonic to pull any rings towards him whenever he nearly reaches them, or an object to either pull Sonic in or push him away.
Sonic 1 Prototype Chaos Emerald.png
$065B76 The graphics for the blue Chaos Emerald are present in the prototype, despite being absent from the special stages proper. The presence of only the blue Chaos Emerald without all the others may imply that the emeralds were planned to all be blue at this point in development, akin to how they are in the 8-bit version.
Sonic 1 Prototype Unused 6th UFO.png
Sonic 1 Prototype Unused 6th UFO anim.gif
$06C8A0 A 6th frame for the animated UFOs in Marble Zone. To properly restore it in the animation script, use the PAR code 011430:0006

Unused Objects

Hmmm...
To do:
Re-Record the video for Object Number 10 or turn it into a GIF; Video is stuttery and could be shortened down to a quick demonstration of the object in a GIF.

The list of objects by offset can be found at ROM address $8580. There are only 94 objects in this build, well below the final's 140.

Object ID Object Name Note
02 and 03 Unknown objects These objects date back to the game's earliest development stages. They don't have graphics, and probably never did. ID 02 is a sort of "pulsating" object, and ID 03 is rectangular in shape. Both have fixed coordinates and cannot be placed anywhere in a level. They have no interaction with the player. Both objects might have served a function back then, but they don't in this prototype, if at all.

Proto Sonic The Hedgehog Genesis early objects anim.gif

04 Unknown object An object similar to ID 03, but animated. It can be placed anywhere on the X axis, but its Y axis is fixed.

Proto Sonic The Hedgehog Genesis obj 04.png

05 Unknown object An invisible object.
06 Unknown object This object follows the HUD. Possibly to test the HUD.

Proto Sonic The Hedgehog Genesis obj 06.png

10 Animation Test An object that seems to test all of Sonic's animations. It jumps to the next animation/sprite when Sonic jumps.

1B Unknown object A static, collisionless object. Whatever it is, it has a variation with another sprite. No graphics exist for either. In the final version, another object with the same ID generates the water surface in Labyrinth Zone.

Proto Sonic The Hedgehog Genesis obj 1B.png

1D Switch An object that acts like any other switch to open a closed passage, only lacking sprites. The best guess for where this would be used is Marble Zone, since that's the only zone in this build that features switch-based interactions of any kind. This object is intact in the final version and remains unused.

Proto Sonic The Hedgehog Genesis early switch mz anim.gif

1E Ball Hog Ball Hog's behavior, as previously mentioned, is different from the final version. It moves around vertically instead of staying in one spot, faces the screen, and drops a singular bomb instead of multiple bombs.

Proto Sonic The Hedgehog Genesis early Ballhog anim.gif

20 Ball Hog bomb A sub-object of Ball Hog, its bombs. It simply drops to the ground, and creates a miniature explosion on impact. The explosion sprites still exist in the final, though unused.
2A Switch door A door that opens by pressing a switch. This object has a variant that is set up to use other tiles, lacks collision, and doesn't react to switches. No valid graphics exist for it. In the final version, this ID is used for a one-way door object in Scrap Brain Zone.

Proto Sonic The Hedgehog Genesis early door anim.gif

2C Jaws Used in the final, but not in the proto. In this build it uses Sonic's palette and can only swim to the left, never to return. Its sprite is loaded in Labyrinth Zone, but is allocated to the wrong VRAM address.

Proto Sonic The Hedgehog Genesis early Jaws anim.gif

2D Burrobot Used in the final, but not in the proto. In this build, Burrobot uses the second palette line instead of Sonic's. It also does not start buried in the ground.

Proto Sonic The Hedgehog Genesis early Burroboy anim.gif

43 Roller Can be accessed via debug mode in Sparkling Zone. Also appears in the unused object layout for Sparkling Zone Act 1. It has different behavior compared to the final version.
  • Uses the second palette line instead of Sonic's.
  • Is completely invulnerable.
  • Moves at a slower speed.
  • Caterkiller's art is loaded over part of Roller's art in the final game, which causes one of the ball animation frames to appear glitched. This doesn't happen in the prototype as Caterkiller's art isn't loaded.
  • Instead of making its entry by rolling on screen, it stands stationary until the player approaches it, to which it then takes off.
  • Doesn't uncurl when it gets close to the player.

Sonic 1 Prototype Roller.gif

4A Special Stage entry This sub-object uses a special effect that was discarded from the final version. It allowed Sonic to enter a Special Stage after touching a giant ring.
4B Giant ring Does not take you to Special Stages.

4F Splats A scrapped enemy accessible via Debug Mode in Marble Zone.

Sonic 1 Prototype Splats.gif

5E Seesaw (SLZ) Only accessible through Debug Mode. Unlike the final version, this object is missing the spiky ball that gives Sonic a boost to reach high places.

Sonic 1 Prototype Seesaw.gif

Unused Object Layout

Hmmm...
To do:
Add in the object layout map, and perhaps attempt at recreating the full chunk layout with what screenshots we have about Sparkling Zone's layout from CES builds. You can find the file for the layout here

Located at 0x729CA is an unreferenced object position list that is presumably used for Sparkling Zone Act 1. Loading it in-game shows a number of differences, including Crabmeats near the entrance which are spawned on top of each other. To load, open the ROM in a hex editor and at 0x70040, replace 2460 with 29CA. You'll then be able to see the changes in SZ1. Interestingly, the object positions seem to match up with an early Sparkling Zone layout seen in screenshots of the pre-WCES and WCES-like builds.

Unused Level

The last level, level ID 06 act ID 00, reserved for the ending cutscene in the final version, has a map of chunks at $6E348 that don't fit any zone very well, nor does it align with any existing stage layout in this build. The game softlocks when accessing it directly, but it can be restored by hacking the layout into a working stage. Interestingly, this map holds 128 chunks and appears to be a normal level. Based on the overall structure, it seems this originally started as an early stage layout, probably dating back to the CES build; however, all level chunks besides 00 (empty space) or 01 (solid wall) appear to have been overwritten at some point, evidenced by the remaining chunks progressing in perfect sequential order going left to right, top to bottom. Whether this was deliberate (i.e. converting the old layout into some kind of test map) or an unintended side effect of other data being written to the ROM is unknown.

Proto Sonic The Hedgehog Genesis unused map 06.png

Unused Palette

Located after Labyrinth Zone's palette is this unused 4-line palette. It seems to've been intended for the Green Hill Zone tileset, as it fits extraordinarily well, with only minor palette errors around rocks and such. The palette is nearly identical to the results screen in the Mega Play version of Sonic 1, which - coupled with this prototype's unused font (which bears similarities to the Mega Play font) - seems to suggest that the Mega Play version was already in development at the time of the Genesis version, or that the leaderboard had been intended for the Genesis version as well. It could've also been intended for the ending due to the 3 pink colors on the fourth line, which appear in the final game's ending. The palette also seems to have been made early on, as the cycling palette's first color is dark blue, which was changed to a grayish blue after the WCES builds.

0x1D9C

S1ProtoNightPalette Screenshot.png
(Source: Sonic Retro)

Unused Code

Plenty of unused code is hidden within this prototype. This includes:

  • An unused routine that makes the Buzz Bomber turn around and loop after flying away.
  • Alternate code for the invincibility stars.
  • Code that calculates square roots, which is also leftover in the final release.
  • Code that doesn't seem to do anything at first, but commenting out a part of it makes Sonic respawn after death.
  • An oddity that makes the goal flash yellow.
  • Some unused title card mappings that aren't used anywhere. Loading it over a normal title card's mappings show it perfectly centered.
Hmmm...
To do:
Create Pro Action Replay, Game Genie codes or address of data location in ROM to enable these. Get a picture for the card mappings as well. Also, there's supposedly a way to see the zone order for the unfinished zones, using FFD004:0D00 to activate it via adding signposts to the unfinished stages. Is this actually pointing to the actual internal level order or is it just reading garbage data?

Beating LZ 1, COZ 1 will bring the player to the next act, beating LZ 2, SLZ 2 also will bring the player to the next act, beating COZ 2 will bring the player to COZ 3 which later became FZ in the final version, beating LZ 3 will bring the player to MZ 1 , beating SZ 3 will bring the player to COZ 1. However, beating SLZ 3 will bring the player to MZ 1. Beating COZ 3 will bring the player to the Sega screen.

SonicTheHedgehogPrototype CESDebugHUD.png
SonicTheHedgehogPrototype ExtendedDebugHUD.png

There are two unused Debug Mode styles in the game's data:

  • One similar to the one seen in various CES screenshots; top four numbers are Sonic's current velocity (only updated on ground) and bottom eight numbers are his current position.
  • Another one which seems to have lost some of its functionality, first line seems to be the current "chunk" Sonic is in (256x256 region) while the third is the upper bit of Sonic's position values. This style also lags the game a lot.

Sounds

There are many unused sounds unique to this prototype, which would go on to be replaced by different sound effects in the final.

Sound $A1

Similar to the sound played when touching Goal blocks in the Special Stage. Replaced by the checkpoint sound in the final release.

Sound $A8

A noise sound effect that then decreases in pitch. Replaced by the aforementioned Goal block sound effect. This sound is used with the unused warping object.

Sound $A9

A longer, higher-pitched version of the rolling sound. Replaced by the sound used for touching speed/Reverse blocks in the Special Stage.

Sound $AD

A duplicate of the "badnik destroyed" sound effect, which lacks noise PSG. Replaced by the air bubble sound.

Sound $B0

A low-pitched siren sound. Replaced by the buzzsaw sound effect.

Sound $B1

A faster, higher-pitched siren which sounds like it was taken straight out of Pac-Man. Replaced by the sound effect used for Scrap Brain's electricity balls.

Sound $B2

Sounds like a buzzer of some sort. Replaced by the drowning sound effect. From 0x7D3EE - 0x7D415. This same sound (albeit with a one-byte difference) can be found in Michael Jackson's Moonwalker (Genesis) starting at 0x68502.

Sound $B3

A rough, low-pitched sound that quickly rises and falls in pitch. Replaced by the sound used by the falling fireballs in the Marble Zone boss fight.

Sound $BA

Resembles the sound used by the color-changing bars in Sonic 2's Casino Night Zone. May have been an early version of the sound used by the color-changing blocks in the Special Stage, which ultimately ended up replacing this sound.

Sound $BF

Two quick, harsh-sounding noises that loop indefinitely. Replaced by the Continue sound effect.

Sound $C2

An alternate version of the "Badnik destroyed" sound effect, with one of the sound channels being a bit harsher. Replaced by the underwater timer "ding" sound effect.

Sound $C3

A deeper version of the bomb explosion sound (which, incidentally, occupies the next sound slot). Replaced by the sound effect used when entering a giant ring.

Sound $C9

A harsh, vibrating noise. Replaced by the noise used when touching end-of-stage point markers.

Sound $CA

Sounds like footsteps walking away; could have possibly been used as an "exit" sound effect for something at some point. Replaced by the Special Stage warp noise.

Sound $D1

A louder version of the waterfall found in Green Hill Zone. This and the next one were completely deleted in the final game. From 0x7DA92 - 0x7DABD. This same sound can be found in Michael Jackson's Moonwalker, starting at 0x6869C.

Sound $D2

A strange rhythmic pounding sound. This and the previous sound doesn't end when playing in-game. From 0x7DABE - 0x7DB09. This same sound can also be found in Moonwalker, starting at 0x686C8.

Music

  • The snare drum and timpani samples used across all tracks are pitched lower than the final release, as the final game had its DAC driver code rewritten to accommodate the "SEGA!" chant, which resulted in all samples being played at a higher pitch. Curiously, the kick drum had its pitch manually lowered in each track in the final game to compensate for the driver change.
Original TR-626 Sample Prototype Final
  • The extra life theme seems to cause various minor issues with the sound driver for a brief moment after it finishes playing.

$85 (Sparkling Zone)

Hmmm...
To do:
Word this section better.
Proto Final

Has a single note difference in the bassline. The final simply reuses a section that's earlier in the track, probably to optimize the song more. The original bassline note is still in the final game's credits medley. A note was also cut slightly shorter in the final version.

$8B (Ending Theme)

Proto Final

Slightly slower than the final track, and a couple of instruments towards the end are held for a bit longer. Goes unused in this build.

$8D (Final Zone)

Proto Final

Goes unused in this build.

$90 (Continue Screen)

Proto Final

Goes unused in this build.

$91 (Credits Medley)

Proto Final

Much of the instrumentation is either slightly different or missing.

$92 (Drowning)

Crashes the game due to using invalid pointers.

$93 (Got Chaos Emerald)

Completely missing; selecting this sound ID does nothing.