Proto:Sonic & Knuckles/Sonic 3C 408

Sonic 3C 408 is a prototype for a canceled Sonic 3 and Sonic & Knuckles compilation that would have been called Sonic the Hedgehog 3: Limited Edition. When this prototype was obtained by drx, the file was labeled "3C," indicating this was a unreleased version of Sonic 3. Due to the late development date, it's obvious this isn't Sonic 3 before it was split into two games.

General Differences

 * Knuckles is selectable in 1-player mode.
 * Tails and Knuckles have incomplete Super forms, since the art has yet to be implemented. Likewise, Hyper Sonic is not in the game yet.
 * The ending sequences have yet to be implemented.
 * No glowing Special Stage rings are present in the S&K zones.
 * The save format is identical to the one found in Sonic 3. You can play a saved game past Launch Base Zone, but when you exit the game, the save will be indicated as "Clear", and only zones 1 through 6 can be selected.
 * Knuckles has a different underwater palette.
 * The music for mini-bosses, Knuckles, invincibility and collecting 1-ups are from Sonic 3.
 * The Super Sonic water shield bounce glitch from Sonic 3 is still present.
 * Pressing A while the game is paused returns you to the level select screen, rather than the Sega logo screen.
 * Many sound effects are missing, especially in the S&K zones and when playing as Knuckles.
 * Monitors placed with debug are Lightning Shield monitors, rather than Super Sonic monitors.
 * Blue Knuckles still appears on the goal signpost when playing as Sonic or Tails. Likewise, a red Sonic is shown on the signpost when playing as Knuckles.

Cheat Codes
Level select is enabled by default, so you can just go down to 'Sound Test' at the title screen.

In the sound test, you can press the following combinations: 01, 03, 05, 07 - Enables debug mode. 02, 04, 06, 08 - Get all the Chaos Emeralds.

You can also use the following patch codes: and - Enable debug mode.

Angel Island Zone

 * Because Knuckles can't shatter the rock that allows access to Sonic's path, he can go that way. However, the boss always spawns in Knuckles' path, causing him to become stuck.
 * Knuckles' route in Act 2 still has its object layouts from Sonic 3.

Hydrocity Zone

 * Knuckles' route in Act 2 has no rings, enemies, or checkpoints.

Marble Garden Zone

 * The Act 1 miniboss crash glitch from Sonic 3 that can be achieved with a second player is still present.
 * The start of Sonic's segment in Act 2 does not have a wall to prevent Knuckles from defeating the Relief, and instead has an extra set of spikes. Knuckles can hurt himself, stand on the spikes during the brief moment of invulnerability, then jump into the Relief's eye and destroy it, allowing access to Sonic's segment.
 * Knuckles can climb on walls during the moving walls sections in both his route and Sonic's.

Carnival Night Zone

 * Knuckles' route in Act 1 still has its object layouts from Sonic 3.
 * Knuckles' route in Act 2 does not end with a Prison Egg, but the teleporter that goes to Ice Cap Zone is functional, anyway.

Ice Cap Zone

 * In Act 1, when Tails first descends while playing as Sonic and Tails, the graphics are screwed up. The snowboard intro overwrites Tails' tiles with the snowboard's, and when the snowboard disappears, Tails' tiles should load. However, Tails' AI is doesn't allow this to happen fast enough, and thus proceeds to draw Tails with some of the snowboard's tiles still remaining. Only when Tails lands does the tile swap complete, and Tails return to normal.

Launch Base Zone

 * The background in Act 1 is a little glitchy.
 * As soon as Knuckles defeats one of the Twin Hammers, the normal Act 1 theme resumes while the other Twin Hammer is still alive.
 * Knuckles does not fight the Big Arm at the end of Act 2, and the boss music does not stop playing when the Prison Egg appears.

Mushroom Hill Zone

 * The level layout is different, and the differences are very noticeable at the start of Act 1. Knuckles starts at the top of the level with Sonic and Tails starting lower down instead.
 * Sonic and Tails just drop down in their standing poses instead of Tails lifting Sonic into the zone.
 * Knuckles does not run into any giant rings at the start of his Act 1.
 * The giant ring in Sonic's area in Act 1 does not flash.
 * If you enter the aforementioned giant ring without all the Emeralds, you'll be sent to the Hidden Palace chamber with Death Egg Act 2 music playing, then instantly warp to a different Special Stage.
 * The lever that Knuckles pulls down repeatedly in Act 2 has a blue handle. In Knuckles' game, the lever doesn't appear at all.
 * A giant ring at the start of Sonic's Act 2 (after the Knuckles cutscene) is missing and has a bit of Russian Roulette action in its place. There are two monitors wedged in the ceiling, and one of them is a 1UP monitor while the other is a Robotnik monitor.
 * The Act 2 boss does not have fire effects when killed until he crashes into the tree, and you must hit him six times after he has zoomed off.
 * During the transition to Flying Battery with Sonic and Tails, Tails won't stop running to the right and will kill himself.

Flying Battery Zone

 * The echo track of Act 1's music will go off-sync after looping, and will slowly drag more and more behind the lead melody as it continues to play.
 * A double set of doors in Act 2 does not open completely.
 * A few level design differences. For example, the pendulums in Act 2 are missing, and in the area after the Act 2 miniboss, there are two ring monitors in place of a red spring, and there are no spikes.
 * Robotnik stops exploding as soon as he begins to fly away.
 * The player does not automatically roll when he busts down the door during the transition to Sandopolis Zone.

Sandopolis Zone

 * The player enters Act 1 in a rolling state, but does not get stuck in the sand. The controls aren't even locked at all, meaning you are permitted to move left or right before you land.
 * Some more object layout differences.

Lava Reef Zone

 * Even more object layout differences.
 * The lava at the end of Act 1 does not cool when Act 2 begins, but you can still walk on it.
 * Act 2's palette has yet to be changed to indicate a freeze-over.
 * The screen does not lock behind your character after having passed the first flamethrower.
 * When you encounter Knuckles, his theme does not play, and he laughs after punching the boulder.
 * The Act 2 boss area does not play the boss theme at the start. It plays it as soon as the boss emerges from the lava.
 * The lava in the boss area does not cool after breaking the Prison Egg. Instead, once the results tally has finished, the platform you're standing on will drift to the right a bit, then you'll have to jump across more platforms as the lava can still hurt/kill you. The level music does not resume, either.
 * The tunnel at the end of Sonic's Act 2 does not go to Hidden Palace, so you're basically stuck. Knuckles' exit to Hidden Palace works, though.

Hidden Palace Zone

 * This zone does not play Lava Reef Act 2's music, but Sky Sanctuary's.
 * The title card refers to this zone as Sky Sanctuary Zone.
 * The player does not run in at the beginning.
 * The screen locks the way back to the starting area after you pass the first set of spikes.
 * A Fire Shield is present in place of a Ring monitor, near the teleporter that leads to Knuckles.
 * In the hidden area, there's a Super Sonic monitor instead of a Ring monitor, and three 1UP monitors instead of one.
 * The Knuckles battle plays the Sonic 3 miniboss music. After defeating Knuckles, the music doesn't stop, and continues to play through the emerald theft scene.
 * At the start of the emerald theft scene, Knuckles just stands on the ground looking upward as Robotnik pulls up the Master Emerald. When Robotnik attempts to escape, Knuckles doesn't hit him, and just grabs on to the emerald.
 * The controls are locked with Sonic looking upward when Robotnik electrocutes Knuckles, but if you use debug you can remove the control lock, though you can't hit Robotnik and you can stand on top of the Master Emerald.
 * After regaining consciousness, Knuckles will charge through the breakable wall, rather than stopping in front of it and punching it.
 * When you approach the teleporter that leads to Sky Sanctuary, the controls and camera won't lock, and Knuckles won't jump on it. You can stand on it to activate it, anyway.

Sky Sanctuary Zone

 * Once again, more level layout differences.
 * The air ducts are not active while Knuckles is en route to enable the bridge in Sonic's Act.
 * There seems to be some palette conflicts.
 * The bouncy clouds don't seem to animate.
 * The screen lock works differently in the GHZ boss fight, and the teleporter emerges in different positions.
 * After the MTZ boss has been defeated, the balloons don't pop until they reach the ground.
 * After defeating Mecha Sonic at the end of Sonic's act, the game cuts straight to Death Egg Zone with no results tally or cutscene.
 * Knuckles' Act does not have any rings, and the teleporter is absent.
 * Pausing and returning to the level select from Knuckles' Act messes up the level select background slightly.
 * As soon as the final boss theme plays, the normal Act 2 boss theme starts up again.
 * Doomsday Zone music does not play in the second half of Knuckles' final boss fight.
 * The screen does not flash when Mecha Sonic becomes Super Mecha Sonic.
 * Some of Super Mecha Sonic's poses are a bit different.
 * When Super Mecha Sonic is defeated, he does not land on the ground and drops off the screen, and nothing else happens after that.
 * The Floating Island overlaps the Master Emerald.

Death Egg Zone

 * The player does not run in at the beginning.
 * The overscan border color for Act 1 is red, instead of black like the other zones.
 * The Act 1 boss overlaps the player, and its laser overlaps the floor.
 * Act 2 ends with a Prison Egg after the Act 2 miniboss is defeated, then the player moves on to The Doomsday Zone, regardless of whether or not he has all of the Chaos Emeralds.
 * The final boss (accessible by selecting Doomsday Act 2 in the level select) is really incomplete, only having a background, a few rings, and various poses of the final boss laid out throughout the act.

The Doomsday Zone

 * Really incomplete, only having the boss graphics and a background with no Super forms available. You can use debug mode and fly over to a section with glitchy collision. The background palette is the same as in DEZ2.

Bonus Stages
At this point in development, the S&K bonus stages are very unfinished and inaccessible in normal play. You can access them via level select.

Magnetic Orbs

 * No collision, partially complete graphics, and a preliminary animating background. As a result, you can only really die there.

Slot Machine

 * More rings, no goal signs when starting the level (the borders still turn into goal signs, though), and a static background.
 * Using debug to fall out of the stage causes the game to crash. In the final, it takes you to a glitchy area with randomly placed tiles.