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Proto:Sonic the Hedgehog 2 (Genesis)/August 21st, 1992

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This is a sub-page of Proto:Sonic the Hedgehog 2 (Genesis).

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

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The August 21, 1992 prototype of Sonic the Hedgehog 2 is quite similar to the Simon Wai build, but is getting closer to the final game. Most of the content is still as it was in the Wai proto (including the presence of Hidden Palace Zone and Wood Zone), but Sonic's sprites have been finalized, some of the bosses have been implemented, and most of the music is finished. Also, pink Casino Night!

This build was released by drx on November 10, 2019 as part of Hidden Palace's Sonic Month.

To do:
Bubbler's Mother, Bubbler, and the metal ball have their code implemented but are unused.
Download.png Download Sonic the Hedgehog 2 (Aug 21, 1992 proto)
File: Sonic_the_Hedgehog_2_(Aug_21,_1992_prototype).bin (2 MB) (info)

General Differences/Notes

  • The level order has been changed from the Simon Wai build.
    • Simon Wai: Aquatic Ruin, Chemical Plant, Hill Top, Emerald Hill.
    • August 21: Emerald Hill, Chemical Plant, Hill Top, Mystic Cave, Metropolis, Aquatic Ruin.
  • Collecting 100 rings still plays music track $88, which was the extra-life sound in Sonic 1 but is now the Casino Night 2-player theme.
  • Bosses for Chemical Plant, Aquatic Ruin, Oil Ocean, and Metropolis have been implemented, but don't load in their respective levels.
  • Tails acts identically to the Simon Wai build.
  • Drowning plays music $8A, which is the Death Egg theme in this build. The graphics for the numbers that display as Sonic drowns also do not appear correctly.

Sound Differences

Most of the game's music tracks have been implemented and all have been finalized, sans the credits theme.

  • While all sound effects are implemented, not all of them are used yet.
  • The spindash sound's pitch-shift messes with some sounds.
  • The invincibility music has a different ending:
August 21 Final
  • The final Hidden Palace song appears twice in the Sound Test as tracks 90 and 9E. The latter slot is occupied by the credits theme in the final version.

Super Sonic

Super Sonic is present in this build and can be easily accessed by destroying the [?] Monitor, which can be added through Debug Mode.

  • Super Sonic already has a cycling palette, but it was not implemented for when Sonic was underwater. This makes Super Sonic retain the normal Sonic color palette underwater.
  • Rings are not consumed while the Super form is active.
  • Super Tails simply gets invincibility.
  • The invincibility is timed, taking the same time as the invincibility powerup.
  • Once the invincibility runs out, Super Sonic is able to use powerup monitors.


To do:
  • Check to see if any of the removed ones have any differences from the Simon Wai build.
  • Create and add level maps.
Oil Ocean Zone
Why is there floating oil?

Emerald Hill

  • The snail badnik from earlier builds has been replaced with Coconuts, though its coding is still present. Interestingly, its ID was changed from $54 to $59.
  • The boss acts near identically to the Simon Wai build, but is now capable of exploding again.
  • The boss plays the Chemical Plant theme. This is because it's still playing music $8E, which was the boss track in the Simon Wai prototype, but has since moved to $93 with Chemical Plant's theme taking its place.

Casino Night

Has the same general design as the Simon Wai proto, but is much more complete. Almost all of the incorrect chunks were fixed, collision was strengthened, and Sonic no longer spawns in the air.

Simon Wai August 21
Sonic2WaiProto BGCNZ.png Sonic2CasinoNightBGAug.png
  • The background was given a major overhaul. The buildings are smaller, making them appear further away, and there's an extra layer at the bottom.
  • The bumper was added.
  • The boss has been partially implemented:
    • The electricity is overwritten with the signpost art.
    • He doesn't attempt to pick up Sonic.
    • Eggman actually moves up, something that doesn't happen in the final game.
    • He spawns right before where the boss arena is in the final.

Hill Top

  • The boss arena is different, and wider than the one in the final version.
  • A small chunk of wall can be found above the boss arena at the top of the level.

Mystic Cave

  • Object placement is now much closer to the final version.
  • The boss acts differently.
  • Crawlton badniks use the second palette line in this build making them look slightly off.
  • Flasher badniks use a simple yellow ball as their flashing animation, while the final game adds shading.
  • Act 2 still has the triple swinging platform.
  • The upper route in Act 2 is much harder than the final game; additionally, the upper upper route from the Simon Wai prototype is in the middle of being removed.
  • Drill Eggman II has more erratic movements than the final.
(Source: Sonic Retro)


  • Somehow, the animation for entering a warping thing has become corrupted in this build.
  • The background and cogs still have their old design from the Simon Wai prototype.
  • Oddly, Act 3's boss seems to better fit Act 2's layout according to the source code.
  • There's an area in Act 1 that can allow the player to fall forever, and eventually the player can accelerate so fast the the game will propel the player up.
  • Lava in this stage does not function yet.
  • Nuts will continue to go up even when reaching above the screws.
  • While the boss is implemented, Act 3 instead has a signpost at the end.
(Source: Sonic Retro)

Hidden Palace

Hidden Palace's layout remains the same as it was in the previous two builds, and still uses the Mystic Cave 2-player music even though the track used in the final is present. However, it did have some behind-the-scenes changes, which seem to suggest there were plans to continue working on it before being scrapped:

  • Stego was added to the debug object list.
  • Vertical wrapping has been implemented for objects (such as badniks), as opposed to the Nick Arcade and Simon Wai prototypes where badniks that fell off the bottom of the stage simply disappeared (see the video to the right).

Wood Zone

Exactly the same as it was in the Simon Wai build. It's still incomplete and ends pretty quickly, with Metropolis' music playing in the background.

Genocide City

Exactly the same as it was in the Simon Wai build... which means it's just an empty level slot with Chemical Plant's music playing.

Death Egg Zone

Exactly the same as it was in the Simon Wai build. Dying here still causes all sound to cut off, unless you activate Super Sonic in which case his theme will play continually until you reset the system.

Special Stage

Unlike previous builds, the Special Stage can be accessed in this build - but there's a catch: It will only load on the Kega Fusion emulator (and some other low-accuracy emulators, including most Android ones), and not modern emulators such as Genesis Plus GX or BlastEm. This suggests that its accessibility is due to emulation errors, which in turn suggests that it won't load if attempted on real Genesis hardware. And even if you do access the Special Stage, there's a chance of it locking up most of the time.

All this aside, the Special Stage here appears to be a very corrupted version of the Sonic 1 Special Stage with the Casino Night music playing. While you can make out what's going on, the graphics are corrupted, making everything pretty hard to see. Hitting a GOAL block or getting the Chaos Emerald triggers a blue screen playing Chemical Plant's music.

Graphical Differences

  • Sonic and Tails' sprites are now their final versions.
  • Stego/Stegway has its updated sprite, but uses the incorrect palette.

Unused Content

To do:
Add graphics for the rest of the objects

Casino Night Block

Sonic2Alpha CNZ Block.gif

An early version of the moving blocks in Casino Night Zone (though only its graphics exist at this point). Oddly enough, it is smaller than the final game.

Metropolis Block

Sonic2Alpha MTZ Moving Block.png

The moving blocks from the Simon Wai prototype can still be placed, though it doesn't move anymore.


You think they overdid the placement a bit?

The infamous Slicer badnik can be also placed in Debug Mode, though it's slightly buggy; it uses the wrong palette line and only attacks when the player is behind it.

Autoroll Object

Sonic2Alpha Autoroll Object.png

This object can be placed in Casino Night Zone and is used in the final game to automatically make Sonic roll in the tubes in Hill Top Zone (or, in the case of Wing Fortress, change the palette).

Chemical Plant/Death Egg Door

Sonic2 CorrectDoor.png

The door for Chemical Plant and (eventually) Death Egg Zone, which also go unused in the final as both levels use the Hill Top Zone version.

Aquatic Ruin Door

Sonic2gen Aquatic ruin door.png

The unused door for Aquatic Ruin Zone in the final also exists.

Chemical Plant Boss

The Chemical Plant Zone boss isn't loaded in said stage yet, but is fully functional when hacked in.

Aquatic Ruin Boss

The boss is near complete, though the totems can not be interacted with yet.

Metropolis Boss

A preliminary version of the Metropolis Zone boss exists.

  • Eggman doesn't move, but will still release his balloons.
  • Balloons act like regular badniks.
  • The orbs around Eggman can be destroyed.
  • There is no win condition for the fight. That means if the boss is beaten, the game will crash.
(Source: Sonic Retro (CNZ block, auto-rolling graphic and bosses))