History Videogame / Sonic3AndKnuckles

* HumanCannonball: A common level feature in Carnival Night Zone are cannons which Sonic can use to be shot to the upper parts of the level. They are also used to transport him to the following zone.

* UselessItem: The Water Shield in ''Sonic & Knuckes'' alone or past Launch Base in the complete game due to every Zone lacking water negating its primary function (making characters immune to drowning). Not ''entirely'' useless (you still get one hit to protect your rings) but very underwhelming compared to the Lightning or Flame Shields. For Sonic he can still make use of the bubble bounce but the Lightning's DoubleJump is more practical and you get the added bonus of ring attraction/electrical immunity and for Tails and Knuckles wearing this shield in those stages is no better than the basic shield from the previous games (if you don't count bullet repulsion, which every shield grants in this game).

* WaterfrontBossBattle: Both of the Hydrocity Zone levels end with a battle where Sonic is in the water, but the boss is above it. For Act 1, the water is deep enough to drown in, and the Big Shaker boss stirs up the water to knock you off your feet. For Act 2, the water is waist-deep, and Eggman uses it to try and pull you into his Screw Mobile's whirling propeller.

* UselessItem: The Water Shield in ''Sonic & Knuckes'' alone or past Launch Base in the complete game due to every Zone lacking water negating its primary function (making characters immune to drowning). Not ''entirely'' useless (you still get one hit to protect your rings) but very underwhelming compared to the Lightning or Flame Shields. For Sonic he can still make use of the bubble bounce but the Lightning's DoubleJump is more practical and you get the added bonus of ring attraction/electrical immunity and for Tails and Knuckles wearing this shield in those stages is no better than the basic shield from the previous games.

* SceneryPorn: Beautiful pixel art, and impressive parallax scrolling on the backgrounds. There are a lot of little cosmetic details to the graphics. The water levels in Hydrocity Zone Act 1 and Launch Base Zone Act 2 match the surface and have different backgrounds below them, leading to a great effect.

* ImmediateSequel: To ''Sonic 2''. This is partially subverted [[AllThereInTheManual in the manual]], as we don't know how much time passed since Eggman landed on the Floating Island and the time Sonic and Tails got there, but played straight for ''Sonic & Knuckles''.

For the first time since 2011, ''Sonic 3 & Knuckles'' has been re-released in the CompilationRerelease ''Sonic Origins'', developed by Simon "Stealth" Thomley of Headcannon, who was previously responsible for the rereleases of ''Sonic 1'', ''Sonic 2'', and ''Sonic CD'' as well as ''VideoGame/SonicMania''. Much like those games, ''Sonic 3 & Knuckles'' has been rebuilt in the Retro Engine developed by Christian Whitehead. In addition to upgrades comparable to the other Retro Engine rebuilds, this release is also notable for another reason: due to, to put it lightly, ''complicated'' legal issues regarding the game's soundtrack (see the [[Trivia/Sonic3AndKnuckles Trivia]] page for the full details), a few of the music tracks have been replaced with Genesis-faithful arrangements of tracks that were originally used in a prototype version of the game and would later be implemented into ''Sonic & Knuckles Collection'', a 1997 PC release of the game. Jun Senoue, who worked on the original game's soundtrack, is said to be responsible for these arrangements, though there's dubiousness with that.[[note]]It's speculated that these are actually even earlier prototype versions than what was leaked, due to some [[https://forums.sonicretro.org/index.php?threads/the-sonic-origins-music-situation.41806/ telling details]], Ice Cap Zone's music being almost identical to the leak's and how every other attempt by Senoue to sound Genesis-authentic ends up sounding like it came out of ''VideoGame/SonictheHedgehog4'', including the confirmed new Super theme.[[/note]]

For the first time since 2011, ''Sonic 3 & Knuckles'' has been re-released in the CompilationRerelease ''Sonic Origins'', developed by Simon "Stealth" Thomley of Headcannon, who was previously responsible for the rereleases of ''Sonic 1'', ''Sonic 2'', and ''Sonic CD'' as well as ''VideoGame/SonicMania''. Much like those games, ''Sonic 3 & Knuckles'' has been rebuilt in the Retro Engine developed by Christian Whitehead. In addition to upgrades comparable to the other Retro Engine rebuilds, this release is also notable for another reason: due to, to put it lightly, ''complicated'' legal issues regarding the game's soundtrack (see the [[Trivia/Sonic3AndKnuckles Trivia]] page for the full details), a few of the music tracks have been replaced with new, Genesis-faithful arrangements of tracks that were originally used in a prototype version of the game and would later be implemented into ''Sonic & Knuckles Collection'', a 1997 PC release of the game. Jun Senoue, who worked on the original game's soundtrack, is responsible for these arrangements.

* DoubleEdgedBuff: You can't use the special moves of the fire, thunder, and water shields if you are invincible.

* BerserkButton: The second stage of Death Egg Zone Act 1's boss, Red Eye, seems to have one: it will start spinning a pair of spiked platforms extremely rapidly while firing off a massive laser beam if you attack it.

Realizing the gem's potential, Eggman decides to use the Master Emerald as a power source to re-launch the Death Egg. Unfortunately, he runs into the Emerald's guardian: Knuckles the Echidna, the last survivor of the ancient echidna clan that once ruled the Floating Island. Knuckles is very naïve due to living in isolation all his life, so Eggman gets an idea: he tricks Knuckles into believing Sonic and Tails are thieves out to steal the Master Emerald. Knuckles agrees to work for him to protect the Emerald, allowing the doctor to hatch his plans in secret.

The plot picks up after the [[UsefulNotes/SegaGenesis Genesis/Mega Drive]] version of ''Sonic 2''. Following the destruction of the Death Egg, Dr. Eggman ([[IHaveManyNames a.k.a. Dr. Robotnik]]) crash lands on the mysterious Floating Island above the sea. The island is able to fly due to its connection with the Master Emerald, a mystical gem of immeasurable power which Eggman intends to steal in order to fuel his space station. When Sonic and Tails arrive to investigate the now seabound landmass, the former is [[DynamicEntry attacked]] by the island's guardian, Knuckles, whom Eggman has tricked into believing that Sonic and Tails are thieves who are out to steal the Master Emerald. The game ends with Sonic preventing Eggman's Death Egg from launching, which causes it to plummet into a volcano cone.

Sonic's campaign culminates in a battle against Knuckles just outside the Master Emerald's altar. When Eggman shows his true colors by stealing the Emerald and electrocuting Knuckles when the latter tries to interfere, the echidna finally realizes the doctor's trickery and helps Sonic chase after the Death Egg before it can leave orbit.

The Knuckles campaign takes place shortly after Sonic's story and features the same levels up to Lava Reef Zone. After that, the player explores an abridged version of Hidden Palace Zone that is devoid of obstacles, which is followed by the final battle against {{Super|Mode}} Mecha Sonic, an Emerald-enhanced version of Sonic's [[EvilKnockoff robotic rival]], on Sky Sanctuary Zone. Knuckles can't run as fast or jump as high as Sonic/Tails, but can access new areas by gliding and plowing through walls that the others can't pierce. The villain is one of Eggman's Eggrobos, rather than the Doc himself.

* AdaptationalExplanation: In the original (and its locked on version), the entrance platform to the Death Egg seemingly detaches from the handle for no reason, despite the Egg Mobile gently falling down. In ''Origins'' and its re-release, the Egg Mobile crashes on the center of the platform, causing the handles supporting it to be destroyed due to its impact.

[[caption-width-right:350:[[An adventure so big, one cartridge wasn't enough.]]

[[caption-width-right:350:[[{{Tagline}} It's 3 times the fun!]]]]

''S&K'' also linked with the ''Sonic 2'' cartridge, allowing you to play ''Knuckles the Echidna in Sonic the Hedgehog 2''. The developers attempted to implement a similar feature with ''Sonic 1'', but found that Knuckles' color palette was incompatible with the game's. Instead, combining it with ''Sonic 1'', or the '97 compilation cart ''Sonic Classics'', expands on the Special Stage (''VideoGame/BlueSphere'') minigame, with over 100 million variations. Locking on any other Genesis game will generate a unique stage.

* OffModel:
** As an NPC, Knuckles has an alternate palette that gives him pink fur and yellow socks. His sprites as a playable character are more accurate to his intended design -- red fur and green socks. Oddly, this is consistent even when playing both games locked on. It seems this is due to palette limitations -- early builds of ''Sonic 3'' have shown that if Knuckles' socks were green, the normally yellow text of the HeadsUpDisplay [[https://tcrf.net/File:SonicTheHedgehog3PrereleaseIntro1.jpg would be green as well]], and having the text turn green whenever Knuckles showed up would have been jarring.
** While watching [[spoiler:the Death Egg fall]] at the end of Launch Base Zone Act 2, Tails has two tiny tails where his normal ones would usually be & two normal ones on the left side of his waist. [[https://s3unlocked.blogspot.com/2018/01/too-many-tails.html Note that this is exclusive to the full game, and Tails doesn't have this issue in a Sonic and Tails game.]]

* {{Faceship}}: The Death Egg is basically the [[Film/StarWars Death Star]] with Eggman's face on it. While one could see what it looked like in Sonic 2's level select, it's at the end of Launch Base and the start of Sky Sanctuary that the thing is seen in clear detail.

* CastSpeciation: Back in ''Sonic 2'', Sonic and Tails controlled the same way. Here, the player can actually make Tails fly to skip platforming areas. Meanwhile, Sonic can trivialize quite a few tough enemies and bosses with the invincibility on his Insta-Shield. On top of that, the elemental shields grant him useful mobility options. Like Tails, Knuckles' gliding and climbing abilities make him useful for platforming, but his low jump can make certain spots more difficult to overcome. The lowered jump height of Knuckles is actually used to seal off Sonic/Tails-only parts of levels, while the reverse is often accomplished via gliding or wall climbing.

* HarmlessFreezing: {{Subverted|Trope}} in [=IceCap=] Zone. The ice will do damage do the player character if they don't escape in time.

** Sonic's SuperMode comes with an ExpositoryHairstyleChange, PowerUpFullColorChange, and PowerGlows. Knuckles and Tails just get the last one. (Downplayed with Tails, who gets four Super Flickies as well).

* WideEyesShrunkenIrises: Many of the Badniks have this kind of look.

** Hyper Sonic and Hyper Knuckles. Not only does the Hyper form make you just as fast as the super form, but you also get secondary abilities; Sonic gets a double jump that creates a flash that kills all enemies onscreen, while Knuckles can glide faster, climb walls faster, and create an earthquake that kills all enemies on screen by gliding into a wall. The Hyper form also lets you breathe underwater, though you'll only see this in a NewGamePlus, because none of the ''Sonic & Knuckles'' Zones actually have any water.
** Super Tails is Tails's equivalent to a Hyper form. In addition to invincibility, he gains an army of Flickies that will shred any enemy that even appears on screen while you just sit there and watch. In ''Sonic Origins'', Super Tails is downgraded to a more standard Super form accessible via the Chaos Emeralds, while the original Super Tails form, still accessible via the Super Emeralds, has been properly rechristened Hyper Tails, putting him on par with the rest of the cast.