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Sonic the Hedgehog 2 (Nick Arcade prototype)

From Sonic Retro

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Sonic the Hedgehog 2 (Nick Arcade prototype)
Prerelease of: Sonic the Hedgehog 2 (16-bit)
System: Sega Mega Drive
Build date: 1992
ROM size: 1 MB
Source: EPROM cartridge
Found by: drx

The Sonic the Hedgehog 2 "Nick Arcade" Prototype is a prototype build of Sonic the Hedgehog 2 for the Sega Mega Drive. It stands as the earliest known version of the game to be found and released onto the internet, likely created during the first half of 1992.

The Nick Arcade prototype is a very early version of the game. Only an untitled Emerald Hill Zone can be played normally, with a further five Zones accessible only through a level select code. Much of the game still looks and plays like the original Sonic the Hedgehog - the level select screen is identical, and remnants of the original Green Hill Zone are still somewhat playable. Sonic 1 music is still intact, and the full Blue Sphere game is available when locked on to Sonic & Knuckles.

History

While perhaps unlikely to have been built for the show, this release is commonly referred to as the "Nick Arcade" prototype due to its appearance in two 1992 episodes of Nick Arcade - the first sightings of the prototype by the Sonic the Hedgehog community. It is also known to have been shown in issues of Sega Visions and, potentially, a behind closed doors press-only event at Summer CES 1992.

The prototype was found and sold to drx in cartridge form for $1,500 USD. The funds were raised via a community effort, with a dump of the ROM going public on November 7, 2006.

Comparisons

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  • Each Zone uses music from Sonic 1, further proving that Sonic 2 was built from Sonic 1.
  • There is a large amount of raw code contained within the ROM.
  • If Tails dies, the camera will follow him as he respawns until he goes off screen.
  • If Sonic & Tails are hit at the same time, lots of rings will sprawl out regardless of how many rings they actually have (provided the player has at least one ring).
  • The backgrounds of Hill Top and Chemical Plant don't move.
  • Invincibility doesn't show stars, but plays the music. The music and invulnerability lasts until the end of the act.
  • Try jump without rolling in a spring pointing to dow and Sonic will use the dying animation while falling. (Tested in Emerald Hill)
  • There is this 8bpp image whose purpose is unknown (located from $1C324-$1FFFF, must be viewed in "two-dimensional" mode in Tile Molester):
S2NA-UnknownArt.png

Green Hill Zone

  • Collision detection is very glitchy, as the collision system has been changed to the system for Sonic 2, but Green Hill Zones collision pointers are still set up for Sonic 1s' collision. Oddly, the old Sonic 1 collision index still exists in the rom, and can be restored via cheat codes (doing this will fix Green Hill Zone, but cause similar collision issues in every other zone in game).
  • You can see here that the Sonic 1 springs still are here in the game and fully functional; the springs in the Sonic 2 levels are different and match the final game.
    • If one passes into Marble Zone (Chemical Plant Zone), the rings will still use the glitchy sprites they had in Green Hill Zone.
    • The spikes used are the same ones from Sonic 2. They use the correct graphics (aside from the green outlines) when seen in Debug Mode but use glitchy graphics when placed or seen in normal gameplay.

Marble Zone (Chemical Plant Zone)

Z dcp01.png
  • Chemical Plant Acts 2 and 3 have the same layout as Act 1, but have the ring and object layouts of Green Hill Zone 1.
  • There are extra objects in the zone for Marble Zone in Sonic 1 accessible via debug, but they use garbled tiles.
  • There is a falling block for Chemical Plant also accessible via debug
  • There is a prototype boss for this zone found in the ROM through hacking.
  • The unused RAW data contained with the ROM is loaded when you down the zone.It does a illegal instrucion error.
    • It loads if Tails falls to the area too.

Spring Yard Zone (Hidden Palace Zone)

  • Act 2 has some leftover object placement from Green Hill Zone Act 2.
  • There is a third act which has water that constantly rises and falls. This zone loads Green Hill Zone Act 1's ring locations.
  • If under water in Acts 2 and 3, or if you use the water level controls with the 2P controller on Act 1 to submerge Sonic until the countdown starts, then jump out, the Labyrinth Zone music will play.
  • In Act 3 you get placed in the blocks, what makes the camera go crazy (after some button mashing you will eventually get placed into the level)
  • In Act 3, shortly after you exit the tube, the water will suddenly appear.

Labyrinth Zone

Z dl01.png
  • An empty zone, it loads Marble Zone's ring layout, Chemical Plant Zone's artwork, and has Labyrinth Zone's rippling effect. Third act is as SBZ3.
  • Labyrinth Zones layouts are very broken, and seems to load broken data from Chemical Plant alongside leftover garbage data. Using debug mode several people have found various strips of "land" but that data is often still just garbage.
  • Several people have debated that this could supposedly be an early version of Genocide City Zone (because of the city-like rippling lines that overlap your character) but somehow got removed from the Simon Wai Prototype. However, it's more likely just garbage data leftover from Sonic 1, as this zone doesn't have any of its own data, besides that which is leftover from Sonic 1.
  • If Marble Zone (CPZ) is loaded first, going back to the level select and going to Labyrinth Zone will cause it to load Chemical Plants background and some of its layout. (some layout tiles are mysteriously missing though)
    • Scrap Brain Zone Act 3 does the same thing, although it loads its own palettes. Oddly, you can easily land on solid ground in SBZ3 if you do this trick, and you can actually go forward by quite a bit (getting to the top of the level and beating it is impossible, though).

Star Light Zone (Emerald Hill Zone)

  • The 4th buzzer's shots (and every other buzzer past it in the level) rarely hurt the player.

Scrap Brain Zone (Hill Top Zone)

  • It is possible to move Tails past the point in Act 2 where it crashes and drop down, transporting you to Act 3.

Final Zone (Hill Top Zone)

  • Hill Top Zone (matching behavior in Sonic 1, where Final Zone is tucked into a corner of SBZ2), crashes to pink if you continue onwards because the game is trying to access the Final Zone boss data which is not there, dead end backwards. If you use debug and continue past the second tree, when you see the pink screen, rapidly press C, at the top of the screen you might see a garbled "illegal instruction" error.

Levels

Cheat Codes

  • Debug Patchcode: FFFFFA:0001. This patchcode removes the need to enter a Debug code. The level select code can be used to debug in any level.
  • Restore Green Hill Zone Collision: With a Game Genie, enter the following codes:
AA1A-CEAL
AA1A-CEFT
AA2A-CEB0
AA2A-CEB6
AA0T-CAG6
AA1A-CAEC
AA1T-CAA2
AA1T-CAF8
AA2A-CADJ
AA2A-CADR
AA1T-DECG
AA1T-DEHN
AA2A-DECN

It restores the original Sonic 1 collision, so Sonic 2 zones will not work.

Downloads

Download.svg Download Sonic the Hedgehog 2 (Nick Arcade prototype)
File: Sonic_The_Hedgehog 2 (Early prototype) (dumped_by_hidden-palace.org).zip (519 kB) (info)

Physical scans

(from drx's Hidden Palace)

External links

References


Sonic the Hedgehog 2 (Nick Arcade prototype), prerelease version of Sonic the Hedgehog 2 (16-bit)
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Main page | Comparisons | Level maps | Hidden content | Technical information

Part of Sonic the Hedgehog 2 (16-bit) development

Sonic the Hedgehog 2 (16-bit)
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Main page (KiS2|2013|3D|Ages)
Maps (KiS2)
Achievements
Comparisons (KiS2)


Manuals
Promotional material
Magazine articles
Reception
Merchandise


Development
Hidden content (KiS2) (2013)
Bugs (KiS2)
Region coding
Hacking guide