Sonic 3 Level Concept Art Research Thread (with HQ Pictures)

UPDATE: I'm updating the main OP with the higher-resolution versions of the images from the Retro Wiki and cleaning up some of the commentary. The images are really large so I'm going to wrap them in quote tags to make the post more readable without sacrificing the image quality.

The relationship diagram informs the dynamics of the plot (credit @Chaos Rush for translations):

• • Sonic
    • Is friends with Tails
    • Is enemies with Eggman
    • Believes Rival/Knuckles is his enemy
    • Is the Legendary god depicted in ancient structures & art of Floating Island
    • Is trying collect the Master Emerald ("Chaos Emerald") so Eggman can't take it
  • Tails
    • Likes Rival because Rival looks like Sonic
  • Rival/Knuckles
    • Thinks Sonic is his Enemy
    • Doesn't know Tails
    • Thinks Eggman is a friend who is interested in protecting the Master Emerald
    • Lives on the Floating Island
    • Protector to the Master Emerald
  • Eggman
    • Enemies with Sonic
    • Is Fooling Rival
    • Wants the Master Emerald

Zone 1 - Woods (Angel Island Zone)

• Knuckles level path in Zone 1 travels underneath Sonic and Tails, just like in the final, including a boss battle underground while Sonic & Tails battle the same boss above
• Sonic and Tails cross the bridge to face the Zone 1 Boss, while Knuckles heads underground for the same fight
• In the final, Knuckles hits a switch that sends Sonic to Hydrocity, but that isn't present in the sketch
• Knuckles in the final just jumps down into Zone 2, but it appears he enters through an underground shortcut in the sketches, starting below the area where Sonic falls through the waterfall

Zone 2 - Sewer (Hydrocity Zone)

• Act 2 of the Zone appears to split with Sonic going above the water and Knuckles maintaining a path underground
• Sonic continues a vertical ascent, eventually Knuckles flushes Sonic upward to the boss encounter instead of downward as in the final
• Sonic's Boss encounter is depicted as a vertical climbing room layout
• A strong current of water forces Sonic to Zone 3
• Knuckles boss fight is pretty close to the final version, with the horizontal layout and apparent rising water level
• There appears to be a door from which the water fills the room - could that have been the intended exit for Knuckles?

Zone 3 - Ruin (Marble Garden Zone)

• Thematically Zone 3 feels a lot like Marble Zone from the sketches
• Zone 3 splits before Act 2, Sonic traveling up with Knuckles traveling underground
• Both appear to hit the same miniboss in different locations
• Zone 3 for Knuckles appears to have some underground magma or water
• The Boss for Sonic was conceived in these sketches with Tails carrying Sonic
• Knuckles and Sonic both have different exits just like in the Final

Zone 4 - Neon (Carnival Night Zone)

• Zone 4 seems extremely Casino Night at this stage
• There is only one miniboss depicted, suggesting Sonic and Knuckles have the same path to start, unlike the Final which features a completely different Act 1 for Knuckles
• No depiction of Knuckles shutting down the lights or a water level
• The path splits for the two in Act 2, with the Elevator being prominently featured
• Sonic is sent up the elevator to the boss fight, before jumping onto the Flying Battery as is passes by to get to Zone 5!
• Knuckles has a unique route after the elevator, unlike the Final where the level simply abruptly ends
• Knuckles was also supposed to have a unique boss encounter, where he has none in the final
• The transporter takes Knuckles to as @Pengi noted, "Zone 5 for Rival" - I will refer to this as 5B

Zone 5 - Airship (Flying Battery Zone)

• Zone 5 shows the progression logically begins at the engine room
• No Knuckles routes found, curiously similar to the final where Knuckles doesn't even battle Eggrobo (we know of course that Knuckles should go to 5B)
• The level path advances upward into the inner workings of Flying Battery, eventually taking you outside to the very top! In the final you appear to basically destroy it when you "fight" Barrier Eggman
• The Boss encounter takes place on some sort of platform that apparently falls off afterward, creating a transition to Zone 6 where you slide down the mountain on the wreckage before it breaks apart and throws Sonic further

Zone 5B - Unknown

• Unfortunately there isn't any existing concept for 5B, since the paper was used to make these adorable concepts of Knuckles including a Black Cat!
• Putting on my Sonic Adventure cap again - these look a lot like character upgrades you get for Knuckles - the digging claw and sunglasses

Zone 6 - Snow Mountain (Ice Cap Zone)

• The aesthetics in the Zone 6 zone sketch contained Christmas-like trees and a Snowman, not unlike the scrapped winter hill! Very fitting for the cheerful theme composed originally, wouldn't you say?
• Apparently Knuckles enters from 5B, beginning underground. This is mostly replicated in the final with Knuckles entering from a transporter direct from Zone 4 after they hastily put together level transitions to move Flying Battery to the SK side of the game
• The miniboss for both appears to be some sort of Snow making machine
• The Act 2 Transition for Knuckles in the final is fairly reminiscent of this sketch, depicting a transition from a long tube that sends the user into the caves below (Ice Cap in the final keeps Sonic above ground for Act 2 with an option to descend into Knuckles path)
• Act 2 features water which matches the final.
• Both paths converge with the same boss fight, just as the final

Zone 7 - Modern Factory (Launch Base Zone)

• Zone 7 shows Sonic traverse the base above ground, eventually leading to a battle with Demolition Robo, which looks a lot like Big Arms
• No depiction of Knuckles throwing a bomb and trying to kill Sonic
• No depiction of Knuckles apparently falling to his death as in Sonic 3K
• After Big Arms, it looks like a scripted cutscene plays out showing the launch, much like the final
• Sonic makes it onto the last platform and either has a battle with Eggman or witnesses the whole thing blow up - Eggman appears to fall to his death but then escapes toward the descending Death Egg which until Origins S3 was unused content
• Zone 8 transition if the falling platform just like the final
• Unlike Sonic, Knuckles seems to go to a Labyrinth Zone underneath Launch Base. (Probably because Launch Base doesn't exist anymore if Knuckles is in a post-game story?)
• Knuckles takes a temple door to Zone 8 instead

Zone 8 - Mushroom (Mushroom Hill Zone)

• Sonic starts Zone 8 much like the final
• Eventually after encountering the miniboss, Sonic is forced into an upper path by the Weather-changing machine that's sort of just there in the final
• After traversing the upper path, Sonic drops through a tree and makes it behind the weather machine, which is the arena for the Boss
• The transition to Zone 9 appears to be the hole in the tree that you run through after defeating Eggman. In the final this transition sees the Flying Battery come in
• Knuckles begins the level above Sonic's path, but is forced underground before encountering the miniboss
• After going through further temples, Knuckles passes by (presumably) a mural depicting Sonic vs Eggman as seen in Hidden Palace in the final
• Knuckles appears to surface just in front of a giant Pyramid surrounded by mushrooms, apparently confirming Zone 8 and Zone 9 are next to one another geographically
• After the respective Boss Battles, both head to Zone 9

Zone 9 - Sand (Sandopolis Zone)

• Sandopolis splits at a chamber which fills with sand, forcing Sonic up and Knuckles down (so Knuckles faces some other boss than Egg Golem)
• Sonic's progression takes him to Zone 10 after a battle with the Egg Golem
• Knuckles has both a unique boss and exit to a 10B! In the final Knuckles sort of just goes to Lava Reef zone without a fully realized level transition

Zone 10 - Volcano (Lava Reef Zone)

• Lava Reef depicts Sonic making his way up to Hidden Palace after crossing the lava flows in Act 1. The boss design is slightly reminiscent of Hot Mobile from Act 2, and is called Lava Generator. The notes say the Lava Cools after the battle (which notably happens twice in S3K).
• Sonic progresses through the cooled magma upwards, finally getting inside of an Echidna temple where the "Showdown" awaits.
• Knuckles serves as the boss fight and then follows the scripted sequence with Eggman stealing the Master Emerald at the end of Act 2
• He appears to destroy the altar of the Emerald, swat Knuckles away, then Sonic is dropped through the Floor created by the collapsing of the palace.
• No Knuckles route, he was supposed to go to 10B instead

Zone 10B - Unknown

• A Knuckles level to be entered from Sandopolis - no concept art exists of this lost zone

Zone 11 - Temple of the Sky (Sky Sanctuary Zone)[/B]

• The beginning of the zone appears to be underground where you run to the transporter to the temple above - either a cutscene or not, both Sonic & Knuckles jump into the transporter
• No Knuckles route here either - looks like Knuckles was supposed to either end the game at 10B or perhaps would have had his own 11B
• No Mecha Sonic depicted here
• It looked like a platforming section could have wrapped up Sky Sanctuary - Sonic jumps debris from the collapsing temple, eventually getting into the gravitational orbit of the Death Egg and landing on the "ceiling" relative to where you start, a bit of a taste of the antigravity gimmicks in Death Egg
• Sonic chases Eggman into the Death Egg - the notes appear to suggest an updside down antigravity boss fight?
• Sonic then follows Eggman into the Death Egg
• In the final, Sonic and Tails jump from the last piece of crumbling infrastructure into the Death Egg, which I always found a little disjointed

Zone 12 - Death Egg (Death Egg Zone)

• Sonic chases Eggman through the Death Egg
• Eventually after beating a miniboss, the elevator takes you further up into Act 2
• After beating another miniboss, you take another elevator up to the heart of the Death Egg (Dynamic Control Device)
• Maybe it's a boss arena or not - it appears to be a large antigravity chamber (reminiscent to me of the antigravity boss from Strider). That room perhaps was repurposed into the Engine Room/Gravity Puzzle from Death Egg 1 in the final which I always thought didn't really make any sense
• Afterwards, Sonic is depicted to transform into Super Sonic and follow Eggman outside the Death Egg (The notes say normally can't fly without Tails)
• The transition to Zone 13 is depicted, but sadly no notes remain

 

You're mistaken - I only asked if someone had documented them already. Unfortunately I'm on Switch so I had a difficult time getting these myself in any good format.

 

Thank you! I will update the OP.

 

Thanks for the feedback, I updated the OP.