Proto:Sonic the Hedgehog 2 (Genesis)/Nick Arcade Prototype

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The Nick Arcade Prototype of Sonic the Hedgehog 2 is a very early build with many visible remnants from Sonic 1, such as level names and music. It is very incomplete, with missing enemies, levels, and graphical glitches everywhere. However, the basic layouts for a few levels have been completed, and Tails has been implemented.

The prototype was sold to drx in cartridge form for $1,500 via a community effort, and was dumped and released to the public on November 7, 2006. It was given its name due to its similarity to a version of Sonic 2 that was showcased on at least two episodes of the game show Nick Arcade, as this build appears to be very close to (if not exactly the same as) the build used on the show.

A video from the show, more specifically the last taped episode, can be seen at right.

General Differences

 * At this point in development, Tails is interdependent: Player 2 is able to control Tails, except Tails will also follow Sonic. Further, Tails cannot complete a level on his own, since the game only loads the goal sign when Sonic approaches it. If Tails gets hurt, he can lose rings for Sonic. The AI is also much simpler.
 * 2-Player mode is even less complete, due to all sorts of odd glitches and not being enabled for every zone.
 * Invincibility doesn't show the star effect, though the music is still played. The music and invulnerability last until the end of the Act.
 * Sonic has different sprites for walking and running.
 * There is a mechanic where Sonic rebounds off walls if he runs into them at high speeds, using sprites that became unused by the Simon Wai prototype:
 * The spin dash is a work-in-progress, as Sonic and Tails can only charge it once; further, the sound for when Sonic spins in Sonic 1 is heard as there is not yet a specific sound effect for the spin dash. Funnily enough, the same behavior was resurrected for the GBA port of Sonic the Hedgehog (complete with non-specific sound effect).
 * The spike damage behavior works the same way as it does in Sonic 1''.
 * The speed cap from Sonic 1 is still present.
 * Locking on this prototype with Sonic & Knuckles will unlock the full "Blue Sphere" game.
 * The timer resets to 9:00 before hitting 9:59, allowing the player to test stages for extended periods.
 * If Sonic and Tails are both hit at the same time, a overabundance of rings pop out of them regardless of how many rings they possess. (As long as the player has at least one ring.)
 * The screen doesn't scroll up or down when you look up or down for a certain period of time.
 * Jumping into a spring pointing down causes Sonic to use the dying animation while falling.
 * All three signposts were originally symmetrical. Only Robotnik's remained that way:

Cheat Codes

 * Level Select - Up, Down, Down, Down, Down, Up, A + Start.
 * Two-Player Mode - On the Level Select, press B + Start on any level.
 * Debug Mode - C, C, Up, Down, Down, Down, Down, Up, A + Start. Debug can also be enabled using Game Genie code . As with Sonic 1, C merely needs to be pressed twice before the final input of Up.
 * Debug Mode and Level Select - Up, Down, Down, Down, Down, Up, UDLR, Up, Down, Down, Down, Down, C, C, Up, A + Start. "UDLR" simply means to press any direction on the D-Pad to reset the cheat detection code. Unlike the final, where both Debug Mode and All Emeralds can be enabled by playing 19921124126 on the Level Select screen, the last Up of the Level Select code cannot "overlap" with the first Up of the Debug Mode code.

Title Screen
The title screen is different, with a particularly well-known design: not only does it appear in the later Simon Wai build, but it appears in the game's instruction manual. The latter instance has the 1-Player and 2-Player options, which would put it around Beta 4.

This version of the logo was retained for the Master System and Game Gear versions.

Zones
At this point in development, the game uses the Zone names and music from Sonic 1. The Sonic 1 title cards are present and intact, but are invisible because the commands to display them are preceded by a return command. Removing the return commands will show the title cards with the Sonic 2 palette.

Green Hill Zone

 * As you'd expect, it's Green Hill from Sonic 1...except now with broken collision, and glitched/missing graphics.
 * Because of the different collision array, most slopes make Sonic fall out of the level and die.
 * The S-bend tubes are broken as well, with the engine treating most of them as invisible barriers.
 * The original collision array data from Sonic 1 is present in the ROM, and can be restored with a set of Game Genie codes: . Using these, it plays perfectly, besides the broken art.
 * All of the necessary data for Green Hill Zone is still present, and has even been updated to use Sonic 2's data formats. For example, the level's tilemaps have been changed from 256&times;256 to 128&times;128, and the art has been updated to look correct in 2-player mode. Unfortunately, this is also one of the main reasons the object art is broken.
 * Act 3's boss has no camera lock, allowing Sonic to go back into the level.
 * All three Acts have different monitors than Sonic 1, showing that the pointers for the monitor types were changed early in development.
 * All Sonic 1-Up monitors are Tails monitors, showing that the Tails monitor in Hidden Palace was supposed to be a Sonic 1-Up as well.
 * Crabmeat has unused art from Sonic 1 in his sprite.
 * The zone still uses the Sonic 1-style springs, whereas the other zones in this build use the Sonic 2 style.
 * The only badnik whose graphics remain intact is the Piranha. However, due to Sonic's palette having been updated, his coloration is glitchy.
 * The spikes are the updated Sonic 2 variants and use the correct graphics when seen in debug mode, but use glitchy graphics when placed or encountered in normal gameplay.
 * Green Hill Zone's palette was not updated to Sonic 2's palette standard, so the spike graphics when viewed in debug mode use one color (a bright green) that is supposed to be gray.
 * If the game is edited so the Rings display correctly, they will also use a wrong color. It is, again, a green, but is supposed to be dark yellow.
 * Tails cannot be harmed by spikes.

Marble Zone (Chemical Plant)
The only other zone seen during the game's Nick Arcade appearances, the CPZ demo was visible in the background of several shots. Until the ROM was dumped, it was the only glimpse of its differences.


 * The background (which does not animate) has a pink tint rather than olive-green, which was probably changed to make CPZ feel more industrialized than it does here. The buildings are also shorter.
 * There are a few objects at the beginning of Act 1, including moving platforms and path swappers.
 * The bubble launchers are in place, but the bubbles themselves are not implemented yet.
 * Transportation tubes do not function properly, letting Sonic fall out to the floor/pit below.
 * The loops have their early diagonal corners. They also do not have the path-swapping objects in place, making them impassible without debug mode.
 * Acts 2 and 3 are identical in layout to act 1, indicating that there wasn't much work completed at this point. They use the same ring layouts as GHZ Acts 2 and 3.
 * There is a prototype boss for this zone in the ROM, which can be found through hacking.
 * Some extra objects from the Sonic 1 Marble Zone are accessible via debug mode, albeit with corrupted tiles.

Spring Yard Zone (Hidden Palace)
Perhaps the most interesting zone that was cut.


 * The level seems to have been worked on while the monitors were still using their Sonic 1 mappings, which explains why there is a Tails 1-up monitor early in Act 1.
 * There are dinosaur and bat badniks present here.
 * Various unused badniks can be placed with debug mode, including the piranha, Stego, Gator, and early Octus. Most have glitched sprites.
 * There is an emerald object which blocks a pipe to nowhere in Act 1. Many thought this was the Master Emerald due to being a large green emerald in a zone called Hidden Palace, but it was actually supposed to be a breakable object like the rocks in Hill Top.
 * If Sonic spindashes into the emerald, he'll drop into the pipe below it. This was fixed by the Simon Wai build.
 * If normally playing Act 1, it stops prematurely due to a slope which is far too steep to climb. If you use debug mode to go past it, there's a little more to see – including a non-functioning water slide.
 * All of the debug mode objects (excluding rings and monitors) have broken previews.
 * Similarly to Green Hill Zone, the palette has one wrong color (A bright green that is gray in all other levels). However, nothing uses the single wrong color here.
 * Sonic's underwater palette is the same as Labyrinth Zone.
 * If you let the drowning countdown begin then jump out of the water, Labyrinth's music will play.
 * Acts 2 and 3 have not been worked on. Act 2 recycles object placement from GHZ Act 2.
 * Player 2 can control the water level by pressing Up and Down.

Labyrinth Zone (???)

 * Uses Chemical Plant's tiles, Labyrinth's rippling, and Marble's ring layouts...and it's completely broken.
 * While there are some strips of "land" (garbage data), it is otherwise like Genocide City and Death Egg in the Simon Wai build.

Star Light Zone (Emerald Hill)
The most complete zone in the prototype, and the only one playable without using the Level Select. On Nick Arcade, contestants played Act 1 and had to collect 25 rings in 30 seconds.


 * Tails is absent from the zone; considering Sonic loses rings when Tails gets hit, this was very likely done to help the players on Nick Arcade.
 * It, like the Simon Wai build, has the only complete Sonic 2 boss thus far. The boss' explosion graphics are from Sonic 1.
 * Both Acts have different layouts, with Act 1's even moreso.
 * Contains the unused charging snail enemy from the later Simon Wai prototype.
 * Spikes that hang from the ceiling don't hurt Sonic if he jumps up to touch them.

Scrap Brain Zone (Hill Top)

 * The background does not animate.
 * The lifts are not fully functional yet, and do not drop like later builds.
 * The lava acts like regular land (i.e., cannot harm you at all).
 * The see-saws copy the center green orb for the weight instead of a flameless Sol, an element seen in a Sega Visions magazine preview:


 * Act 1's layout is complete, but the playfield limit has not yet been changed from Sonic 1. As a result, the Act cannot be finished because there is a spin pipe leading to death.
 * Act 2 cannot be completed with Sonic, because if the camera moves past X coordinate, the game tries to load pattern cue , which references data that is not a pattern load cue, causing the game to read garbage art data as a pointer and subsequently crash. As the event handler is specifically looking for Player 1's camera X position to trigger the event, however, Tails can complete the Act.
 * Removing the art load cue will allow Sonic to go further into the level, but shortly after that it simply stops abruptly. After the point that triggered the art cue is reached, the player can fall off the level to go to Act 3, a remnant from Scrap Brain Act 2 in Sonic 1.
 * In Sonic 1, Scrap Brain Act 3 is actually Labyrinth Act 4. Labyrinth in this build is broken and uses Marble/Chemical Plant's graphics, so this level does as well. The exit to Final Zone is still present, and can be activated by hugging the top of the level and moving to the right via Debug Mode.

Final Zone

 * Hill Top's graphics are used. The Sonic 1 Final Zone used the graphics of Scrap Brain, so this is unsurprising.
 * Going left drops you over an edge to a dead end.
 * Moving too far to the right crashes the game with a purple screen. This is because the game tries to load the art for the final boss by loading art cue which does exist, but references data that is not a pattern load cue, causing the game to read garbage art data as a pointer and lock up.
 * Through hacking to disable the boss' art load request, it is possible to play further into the Zone. The Sonic 1 final boss' object number will load, but the boss' code is gone and replaced with a dummy object. Because of this, there's nothing to fight and hence no way to reach the "ending".
 * The level layout is actually that of Hill Top Zone Act 1, with no rings or objects. Playing past the point where Act 1 would normally end will simply lead you to a pit. Going past the pit with debug mode will lead to a bunch of nothing before the beginning of the level layout loops over.
 * Beating the level by hacking a signpost into it sends you to the SEGA screen. This is consistent with Sonic 1, as the ending could only be triggered by beating the boss.

Special Stage

 * The game crashes while loading due to bad pointers and missing art, but most of the code is based on the Sonic 1 Special Stage.

Object List/Source Code
A humongous object list can be found inside the ROM, along with some raw source code.

Something interesting to notice is this group of code:

These lines of code are in the block that makes up Hidden Palace Zone's debug list from an earlier build. The content in the list however, appears to be identical to the actual compiled version in the ROM. It does however, give us infomartion on the objects in the zone that may have been previously unknown:
 * Redz is the red T-rex badnik that appears in Hidden Palace Zone. Interestingly, this is the only badnik whose name does not correlate to the animal species it's based on.
 * Bfish is the jumping fish badnik that was unused by the Simon Wai prototype.
 * Seahorse is Aquis, the seahorse badnik that was in the final game in OOZ.
 * Skyhorse is most likely the second aquis object in HPZ's debug list - The version that shoots a harmless projectile.
 * Stego is the triceratops badnik that was unused by the Simon Wai prototype.
 * Wasp is Buzzer, the bee badnik that's in EHZ in all known versions of Sonic 2. In this prototype, it also has a home in HPZ's debug list.
 * Gator is the Alligator/Crocodile badnik that is unused by the Simon Wai prototype.
 * Bbat is the dive-bombing bat that appears in Hidden Palace Zone.
 * Oct is Octus, the Octopus badnik that was in the final game in OOZ.

These same lines are duplicated in the debug list for Emerald Hill Zone, but unused because the game is told that EHZ's debug list will have 18 entries, and the HPZ enemies are all after entry number 18.


 * This chunk of uncompiled code also indicates that the zone order present in this build was going to be changed even this early stage; Emerald Hill Zone's debug list is labeled as Zone 00, which is Green Hill Zone in this build, but Emerald Hill in later builds. Similarly, Hidden Palace is indicated as Zone 08, which is where it resides in later builds and the final.