Summary

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Sonic 2 Prototype Summary

Facts regarding the prototypes have been compiled into this document. Significant bits are in bold. This is not meant to be a complete list of differences between the prototypes and the final version. Insignificant details or way-too-obvious discrepancies are not included.

Sonic the Hedgehog 2 Nick Arcade Prototype

General

• If Sonic runs into a wall with a high velocity, he will bounce back off of the wall. This feature was ultimately canned, but it uses unused sprites that remained in the later beta.
• 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.
• Tails can lose rings for the player if he is hit by a badnik.
• Similar to the other prototype if Sonic & Tails are hit at the same time lots of rings will sprawl out regardless as to how many rings they actually have (Provided the player has at least 1 Ring)

Green Hill Zone

• The zone from Sonic 1 is included, with its level art converted to Sonic 2's format (128x128 blocks rather than Sonic 1's 256x256s) and the necessary changes have been made to make loops work.
• Green Hill has collision detection, albeit it's very glitchy, detecting hills that don't exist, among other things.
• A Tails Life Monitor is present just as it is in Hidden Palace Zone.

Marble Zone

• Actually Chemical Plant Zone, the zone is heavily under development, with major differences in level design from the final or from the later prototype, is buggy and unfinished generally.

Spring Yard Zone

• Actually Hidden Palace Zone, the zone pretty much as it is in the later prototype and in the final since no work was ever done to it throughout its lifetime.
• Hidden Palace Act 2 has some leftover object placement from Green Hill Zone Act 2.
• There is a third act, as well, which has water that constantly rises and falls. This zone loads GHZ Act 1's ring locations.
• If you stay in the water in Acts 2 and 3 until the countdown starts and come back up, the Labyrinth Zone music will play.
• The level of water in Acts 2 and 3 can be controlled using up and down on the 2P controller.

Labyrinth Zone

• An empty zone, it loads Marble Zone's ring layout and Chemical Plant Zone's artwork, has Labyrinth Zone's rippling effect. Third act is as SBZ3.
• Labyrinth also lacks collision detection and is therefore unplayable, a la Genocide City Zone.

Star Light Zone

• Actually Emerald Hill Zone (which the later prototype confirms kept the name Green Hill Zone for a time) which is as it was in the Nick Arcade video, with minor differences to the final level layout.

Scrap Brain Zone

• Actually Hill Top Zone, this zone is also under heavy revision, as it finishes with a pipe leading to instant death. Second act crashes after a section which ought to have an earthquake effect.

Final Zone

• Hill Top Zone (matching behavior in Sonic 1, where FZ is tucked into a corner of SBZ2), crashes to pink if you continue onwards, death pit backwards.

Sonic the Hedgehog 2 Simon Wai Prototype

General

• Sonic 2 was built based on Sonic 1. Therefore many Sonic 1 elements were carried over to this prototype.
• This is a very early version of prototype. It's more of an "alpha" than "beta".
• The prototype ROM has been tempered with by pirates, who have removed the Sega and Sonic Team credit at startup.
• Sonic 1's "Sega" logo and voice is played after a demo or game is over.
• Holding up or down keys for a while will not temporarily make Sonic look up or down.
• Getting 100 rings plays Death Egg music.
• Canceling out-of-breath countdown plays Emerald Hill music.
• Invincibility plays Super Sonic music.
• Super Sneakers, while still does the job, only speeds up the zone music a little bit.
• Tails can destroy monitors, with the effects applied to Sonic.
• Tails loses rings on Sonic's behalf.
• Tails does not actively seek for Sonic but merely copies Sonic's moves with a constant delay.
• When Sonic and Tails are attacked at the exact same time, massive loads of rings come out.
• Tails cannot fly.
• Tails uses Sonic's icon in 2P mode.
• Tails does not walk up to Sonic when a level begins.
• Spindash charge-up sound effect is the same as normal spinning.
• Spindash release has no sound effect.
• Objects placed are vertically flipped if Sonic is upside-down before entering debug mode.
• Restart points can be placed using debug in certain zones.
• Some zones' music are playable in level select screen, even though their names don't show up in the level list.
• There is a prototype screenshot right in the Sonic 2 manual.

Chemical Plant Zone

• Corners of loops are shaped differently.
• An earlier prototype has different layout.
• A background building is different in an alpha prototype.
• An unused animation of Robotnik getting splattered by blue chemical is found within the prototype ROM through hacking.

Green Hill/Emerald Hill Zone

• When fighting the boss, Sonic's graphics are messed up if he has invincibility or shield.
• Boss flies straight down, instead of coming from the right as in final version.
• Boss has no helicopter sound effect.
• You can place a lost sprite, the high-tech star post, in this zone through debug.
• An earlier prototype has different layout.

Hidden Palace Zone

• The big green emerald ("Master Emerald") is only a breakable object blocking the tubes.
• Tails 1-up monitor does give Sonic an extra life, whereas the one in final version doesn't.
• Emerald Hill music is played after breathe counter is cancelled.
• A magazine screenshot of Sonic running off the ramp is a mock-up.
• An earlier, playable, version might be using different background.
• The trycerobot enemy is found within the prototype ROM through hacking.
• The final Hidden Palace Zone is the same as our prototype, with auto-spin at tube entrances.

<Unnamed Desert> Zone

• No credible evidence to support this level is called Dust Hill Zone.
• The only screenshot released from Sega featuring a desert level turned out to be a mock-up.
• The crocobot enemy is found within the prototype ROM through hacking. It may, or may not, be intended for this level.
• Little of this level was ever made. Presumably scraped before a playable version was created.

Hill Top Zone

• Sonic doesn't spin when going through tunnels.
• There is no earthquake sound effect.

Neo Green Hill/Aquatic Ruin Zone

• Water level is shallow.
• Sonic's water-splashing animation is messed up.
• Tails triggers no water-splashing animation.

Metropolis Zone

• Pistons don't throw you very high up.
• Metal crushers and fire cannot hurt Sonic.
• Sonic falls through most of the rotating nets, but one of them does work.
• Sonic can rotate a nut upwards pass the height of the supporting screw pole.
• Act 3 has a special lift that was cut from the final game.

Oil Ocean Zone

• The sun scrolls with the background, and is non-animated.
• Wooden balls did appear in Sonic 1 prototype.
• Two seahorse enemies are found within the prototype ROM through hacking.
• An unused, shoot-and-flee octopus enemy is found within the prototype ROM through hacking.

Wing Fortress Zone

• Known as Sky Fortress Zone at one point during development.
• Music is present in our prototype.

Genocide City Zone

• Level is empty. Presumably canned at the very early stage of development.
• Apparently, no screenshot of this zone, mock-up or otherwise, was ever published.
• There's a slight graphical glitch involving a purple object in 2P.

Wood Zone

• Yes, we know the upper part of the level features conveyor belts, a series of small platforms, and flowery railings.