History WhatCouldHaveBeen / Sonic3AndKnuckles

* During development, Sonic Team experimented with different moves for Sonic, such as a ring attack, an air dash (which would be kept as the Fire Shield's ability and one of Hyper Sonic's abilities) and even a move that is extremely similar to ''VideoGame/SonicMania'''s Drop Dash, before ultimately setting on the Insta-Shield seen in the final game.

* A theoretical ''Knuckles the Echidna in Sonic the Hedgehog'' was going to be accessible by locking the game to ''Sonic 1''. However, this idea was scrapped, mostly due to palette issues (as all the in-game graphics used Sonic's palette as a base) and bugs involving the gliding mechanic in Scrap Brain Zone. [[https://www.gameinformer.com/b/features/archive/2016/10/10/how-sonic-the-hedgehog-3-became-two-games-sonic-and-knuckles-lock-on-technology.aspx Interviews also state]] the developers did not consider Knuckles' gameplay enjoyable enough in ''Sonic 1's'' more cramped level design. Naturally, in the decades since then, there's been a ROM hack or several that fixes both of these problems. In the mobile remaster of ''Sonic the Hedgehog'', Knuckles is playable, and can be unlocked by collecting all six Chaos Emeralds.

** At another point, Knuckles would have been an hedgehog, and Tails would have been fond of him due to his resemblance to Sonic. The "hedgehog rival who resembles Sonic" concept would be used years later with [[VideoGame/SonicAdventure2 Shadow the Hedgehog]].
* A piece of level ConceptArt briefly shown in a promotional video depicts Super Sonic fighting a dragon-like monster in space, suggesting that this would have been the final boss faced in The Doomsday Zone, before being replaced with Eggman's spaceship and mech. This is further supported by the Japanese ''Sonic 3'' manual mentioning a mural near the Emerald Altar predicting the coming of a legendary dragon that would bring great disaster, and said mural being shown in early level sketches. The player gets to visit the altar in the final ''Sonic & Knuckles'', but there are no more references to the dragon's legend, seemingly replaced with a mural predicting the battle with Eggman's final mech in space. However, the plot point and concept seem to have been picked up years later by ''VideoGame/SonicAdventure'', which upon revisiting Angel Island's lore showed [[https://info.sonicretro.org/images/2/2d/SA1_PerfChaosMural.PNG a similar mural]] depicting a dragon-like monster destroying a city, and culminated in a final battle as Super Sonic against said monster (revealed to be Chaos' [[OneWingedAngel final form]]).

* Following the publishing of the proof of concept video, Stealth wrote [[https://hcstealth.tumblr.com/post/100311283757/sonic-3-knuckles-20th-anniversary a post-mortem]] discussing the technical aspects of the demo, as well as some ideas he would like to implement for the full game. While a few of his ideas were realized with ''Origins'', some did not:

* Hidden Palace Zone was seemingly going to be part of Lava Reef Zone rather than its own zone, explaining why it shares its music with the latter's second act and is labelled as "Lava Reef 4" in the level select. There was also going to be tiny critters around the Emerald Altar, possibly Chao prototypes.

* ''Sonic 3'' and ''Sonic & Knuckles'' were originally intended to be a single game. However, a deal between Sega of America and [=McDonalds=] for a Sonic toy tie-in forced the devs to release the game when it was only half done. To keep the original ambitious vision, Sonic Team decided to split the game in half, saving Knuckles and half the levels for the second part. The Lock-On Technology was developed to allow to combine the games into one as originally intended.

[[quoteright:323:https://static.tvtropes.org/pmwiki/pub/images/346px_sonic3_potentialknuckles_conceptart.png]]
[[caption-width-right:323:Early Design of Knuckles when he was originally a mole with sunglasses for when he was on land.]]

[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/afc35083_3d37_4dbe_aeb2_253d862ae8db.gif]]
[[caption-width-right:350:Left: Hydrocity as it appeared in the prototype\\
Right: Hydrocity as it appeared in the final game.]]

* A piece of level concept art briefly shown in a promotional video depicts Super Sonic fighting a dragon-like monster in space, suggesting that this would have been the final boss faced in The Doomsday Zone, before being replaced with Eggman's spaceship and mech. This is further supported by the Japanese ''Sonic 3'' manual mentioning a mural near the Emerald Altar predicting the coming of a legendary dragon that would bring great disaster, and said mural being shown in early level sketches. The player gets to visit the altar in the final ''Sonic & Knuckles'', but there are no more references to the dragon's legend, seemingly replaced with a mural predicting the battle with Eggman's final mech in space. However, the plot point and concept seem to have been picked up years later by ''VideoGame/SonicAdventure'', which upon revisiting Angel Island's lore showed [[https://info.sonicretro.org/images/2/2d/SA1_PerfChaosMural.PNG a similar mural]] depicting a dragon-like monster destroying a city, and culminated in a final battle as Super Sonic against said monster (revealed to be Chaos' [[OneWingedAngel final form]]).

* An early [[https://sonicretro.org/2022/03/22/early-knuckles-the-echidna-art-and-details-emerge-from-newly-uncovered-internal-document/ character document for Knuckles]] describes a scrapped ability to create whirlwinds to break down walls. This idea was scrapped, but the ability might have been given to Espio in ''VideoGame/KnucklesChaotix''.