The Nick Arcade prototype version of Sonic the Hedgehog 2 is the earliest known pre-release version of the game, predating the famous Simon Wai prototype. This prototype receives its name from the game show Nick Arcade due to an earlier version of Sonic the Hedgehog 2 being showcased in two episodes where its build seems similar to the latter prototype, if not the same version as used on the show.
Notably, this prototype shows that Sonic the Hedgehog 2 is based off of the original Sonic the Hedgehog. For example, the Green Hill Zone in this prototype uses the same music as in the Star Light Zone.
- If Sonic runs into a wall while running at a fast speed, he will bounce back off of the wall. This feature was scrapped sometime after this build, but the sprites it uses are still present in the Simon Wai prototype.
- Sonic and Tails are in different symmetrical designs on the end signpost.
- Each Zone uses music from the original Sonic the Hedgehog.
- Tails can lose rings for the player if he is hurt.
- If Tails dies, the camera will follow him as he respawns until he goes off-screen.
- If Sonic and 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.
- When obtaining Invincible, stars are not seen but the music still plays. The music and invulnerability both last until the end of the act.
Green Hill Zone
- Despite this Zone being in the original Sonic the Hedgehog, it appears in this prototype with the correct format for Sonic the Hedgehog 2.
- Because this Zone was originally in the original Sonic the Hedgehog, and the collision detection is different in that game from Sonic the Hedgehog 2, Green Hill's collision detection is very glitchy. However, the collision detection for the entirety of the original Sonic the Hedgehog is present in the ROM and can be accessed through a variety of cheat codes. Unfortunately, while this does fix the collision detection in Green Hill, it breaks it in all the other Zones.
- Tails Life Monitors are present just as one is in Hidden Palace Zone, as all the monitors in Green Hill Zone haven't been changed to use Sonic 2s' monitor system. As a result, nearly every monitor in Green Hill Zone has been "switched" with a different monitor.
- The springs from both Sonic games appear in this zone. Only the Sonic 2 springs appear in the released version.
- Many badniks and obstacles use glitchy sprites, including rings.
- The Crabmeat badnik uses a lost sprite from Sonic 1.
- The rings' glitchy sprites from this zone will be carried over to Marble Zone if the player advances to the latter zone.
- The spike placements are identical to Sonic 2's final version. The sprites appear glitchy during gameplay but the template is mostly identical when using Debug Mode.
- The boss for the zone also uses glitchy sprites, as well as using the same lost sprites as the Crabmeats in place of Robotnik's face.
- Tails can stand on the spikes without getting hurt.
- This is Chemical Plant Zone, and it is heavily under development, with major differences in the level's design from either final or the later prototypes, and is very unfinished.
- Marble Act 1's terrain layout and background are identical to Chemical Plant act 2 and act 3. The latter two's object placements are copied from Green Hill Act 1.
- It uses a pink palette instead of a green palette used in the later betas and final versions.
- Some of the buildings in the background are shorter, and match that of the footage of the Nick Arcade build.
- Extra objects and the falling block from Chemical Plant are accessible for this zone with debug mode. However, the former's graphics appear to be incorrect.
- The transportation tubes were apparently used in a different way, but they aren't functional in this build.
Spring Yard Zone
- Actually Hidden Palace Zone, the zone layout is as it is in the later Simon Wai prototype.
- The object layouts of Green Hill Act 2 are carried over in Spring Yard Act 2.
- Act 3 includes water, which appears after the player exits the tube. The water repeatedly falls and rises throughout the level. This level's starting position is inside the blocks, therefore the camera will appear faulty unless the player presses a few buttons.
- The location of Green Hill Act 1's rings are carried over to this zone regardless of which act.
- The Labyrinth Zone's music is heard if the player triggers the countdown while under water in Act 2 and Act 3
- The water level can be controlled using the 2P controller.
- If you move the water up so a badnik is submerged, his orange spot turns bright yellow. This is because Sonic's underwater palette is really from Labyrinth Zone in Sonic 1.
- All of the debug mode objects besides rings and monitors have broken previews.
- There is a strange bouncing object using the bat's graphics found in the debug list.
- It has two objects that uses the animals' graphics. One only flips, the other flips and shoots fire.
- The other one looks like the unused Stego.
- There is no terrain to be found in Labyrinth zone. Even if there is "terrain" the images and data appear to be faulty. However, the ring locations of Marble Zone, Chemical Plant's background, and the rippling effect can be found here. Labyrinth's Act 3 is a copy of Scrap Brain act 3.
Star Light Zone
- Actually Emerald Hill Zone and is as the same as it was in the Nick Arcade video. The layout is very different in Act 1, and slightly different in Act 2. Star Light Zone's music plays in this zone.
- This is the only zone where Tails is disabled, suggesting this particular version was tailored for the Nick Arcade show in order for the contestants not to have their rings lost by Tails, as well as hide the fact that he can follow the player, as this feature hadn't been directly featured previously. Tails can play in this zone via 2 player mode, though.
- The boss behaves exactly the same as in the later prototype, but it does have explosion effects. These are the same as the ones from Sonic 1.
- The player is almost unaffected by the orbs that the fourth Buzz Bomber onwards shoots.
Scrap Brain Zone
- Actually Hill Top Zone, this zone is also under heavy revision, as it finishes with a pipe leading to instant death because the screen-limit has not been changed yet.
- The playfield limits are still the same as they were in Sonic 1, but the level does not end at these limits. As a result, Act 1 cannot be played through.
- The secondary collision array for Act 2 is missing, so as a result, loops don't work.
- Second act crashes at about the midpoint. This is because, as Sonic 2 is built off of Sonic 1, the level event handler calls a subroutine from Sonic 1 that no longer exists (the transition between Acts 2 and 3 of Scrap Brain Zone). Final Zone crashes at the second tree for the same reason.
- The lava does not hurt the player in this prototype.
- Green orbs are used as the weight on teeter-totters instead of a Sol without fireballs.
- The lifts are not fully functional yet and partly broken
- Letting Tails drop down at the end of Act 2 will still force the player to the next Act.
- Act 3 also has no terrain, but the color palletes are still correct. The top exit for Scrap Brain Act 3 is impossible to reach.
- The Hill Top Zone's terrain and background layouts are positioned on the rightmost edge of Scrap Brain Act 2, in the same place as the Final zone. Because the boss data for Final Zone has been deleted, the game will crash and a pink screen appears if the player advances past the second tree. If the player uses debug mode in this area, repeatedly pressing the button on a Sega Genesis console while the screen is pink will create an "illegal instruction" error. The error's graphics are incorrect however.
- Same as Sonic 1
- Unplayable (crashes to lila)
- Playing music in the sound test and then selecting this has a 46.8% chance of carrying an infinite note
- In the episode of Nick Arcade featuring the prototype (see the video below), a younger Melissa Joan Hart is seen playing a brief section of this prototype. In this challenge she had to collect 25 rings in Emerald Hill Zone Act 1 in 30 seconds.
- at The Cutting Room Floor
- at Sonic Retro