[[quoteright:350:http://static.tvtropes.org/pmwiki/pub/images/SonicAdventureCover_8990.jpg]]
[[caption-width-right:350: The fastest thing alive makes the comeback of a lifetime.]]

Created as ''[[KillerApp the]]'' [[KillerApp launch title]] for the UsefulNotes/SegaDreamcast, and the highest selling title for the system, ''Sonic Adventure'' is one of the first 3D games in the ''Franchise/SonicTheHedgehog'' series [[note]]Earlier entries such as ''VideoGame/Sonic3DBlast'' and ''SonicJam'' do not count, as the former [[DigitizedSprites was not real time 3-D]] (sans the special stages on the Sega Saturn port), and ''Jam'''s 3D world wasn't a full 3-D game, but a very early test of the ''Sonic Adventure'' engine, and while ''VideoGame/SonicR'' and ''VideoGame/SonicTheFighters'' used real time 3D, they were spinoff titles with different gameplay styles than the main series [[/note]]. It was released in Japan on December 23rd, 1998, receiving releases in North America, Europe and Australia between September and December of 1999.

''Sonic Adventure'' was designed to be to Sega and ''Franchise/SonicTheHedgehog'' as ''VideoGame/SuperMario64'' was to Nintendo and ''Franchise/SuperMarioBros'': a KillerApp designed to be the VideoGame3DLeap to an established mascot franchise that would not only showcase the potential of their flagship console, but also [[WinBackTheCrowd revitalize their flagship series and their own reputation]], after they had [[DorkAge fallen into both a creative and financial rut]] during their rocky UsefulNotes/SegaSaturn years.

Mad scientist [[BigBad Dr. Ivo "Eggman" Robotnik]] has a new plan to TakeOverTheWorld: releasing an ancient morphogenic creature known as "Chaos" [[SealedEvilInACan from its confinement]] and using the seven [[MineralMacGuffin Chaos Emeralds]] to empower it to world-conquering levels.

Standing between him and his maniacal goals are a team of six heroes, whose adventures unfold in a RashomonStyle plot:

[[AC:Playable Characters and their gameplay types:]]
# '''Sonic the Hedgehog''' -- a sarcastic but virtuous blue hedgehog capable of running at supersonic speeds. Sonic's gameplay style is the most reminiscent of the side-scrolling games: Just get to the goal (which is sometimes an animal capsule reminiscent of the Genesis games, sometimes a Chaos Emerald, occasionally just an end area).
** '''Super Sonic''' -- As in other games, the GoldenEnding requires powering Sonic into his SuperForm and taking out the TrueFinalBoss.
# '''Miles "Tails" Prower''' -- Sonic's lil' two-tailed fox buddy, a young genius with an aptitude for building machines on par with Robotnik's creations. All of Tails's stages pit the player against Sonic (and later Robotnik) in a race to the end of the stage. The stages are just a single section of Sonic's stages, hopelessly broken by Tails' flying ability. [[TheComputerIsACheatingBastard Sonic is a cheating bastard]] for this very reason, but even speed boosts can't help him.
# '''Knuckles the Echidna''' -- current Guardian of the Master Emerald. When Chaos is released from the Emerald, it is naturally broken into pieces. Angel Island falls from its place in the sky and into the sea, and Knuckles takes it upon himself to track down the missing pieces and restore the Emerald (and Angel Island) to its former glory. Thus, the goal of each of the echidna's stages is to find three shards, using his SpiderSense to pinpoint their locations. Reappeared in ''VideoGame/SonicAdventure2'' for Knuckles and Rouge.
# '''Amy Rose''' -- a pink hedgehog with [[StalkerWithACrush an all-consuming crush on Sonic]]. After she meets a young bird on the run from one of Robotnik's robots, Amy resolves to return the bird to its family. In her stages, Amy must outrun [=ZERO=], the robot in pursuit, and get to the giant balloon that will carry her away. [=ZERO=] is actually ''not'' after Amy, but instead the bird, who unbeknownst to her, has a Chaos Emerald in its locket. Amy is not very strong or agile, and carries a mallet for protection.
# '''Big the Cat''' -- a lazy but warm-hearted fisherman. After his pal Froggy swallows a strange looking jewel and runs away from home, Big chases after the frog. The goal of each of his stages is to fish Froggy out of a body of water; there is little danger posed to Big himself. Nevertheless, Big's fishing pole can double as a weapon.
# '''E-102 γ (Gamma)''' -- one of Robotnik's most advanced robots, who eventually turns against its creator. Shoots things up to get to the end of the stage before time runs out, which can be increased by [[{{Combos}} combo-killing]] multiple enemies at once. Like Knuckles', this also was re-used for Tails and Robotnik's modes in ''VideoGame/SonicAdventure2''.

Re-released for the UsefulNotes/NintendoGameCube and PC in 2003 as ''Sonic Adventure DX: Director's Cut'' (ironically [[SequelFirst after its sequel's remake]]), which added special missions and unlockable GameGear games. As of September 15th, 2010, it is now available for purchase on UsefulNotes/XboxLiveArcade and {{PlayStation Network}}, with the ''DX: Director's Cut'' extras [[DownloadableContent sold separately]][[note]]but does not come with the GameGear games[[/note]]. Roughly half a year afterwards, it also saw a release in this manner on UsefulNotes/{{Steam}}.

A direct sequel, ''VideoGame/SonicAdventure2'', sold in 2001 to commemorate the series' [[MilestoneCelebration 10th anniversary]], and rumors of a third iteration of the ''Adventure'' series linger on, though some argue that ''VideoGame/SonicTheHedgehog2006'' was "''Sonic Adventure 3''" in everything but name.

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!!Tropes:

* AbsurdlySpaciousSewer: Averted with Station Square's sewers, played straight with those of Casinopolis (you get dumped in there if you lose a game of pinball and come away with less than 100 rings or you play the level as Tails).
* AbusiveParents: Pachacamac didn't have any qualms in ordering his echidna soldiers to trample his own daughter just to get to the Emerald shrine.
* ActionHoggingOpening: The FMV intro looks ''far'' more epic and impressive than most the story depicted in game.
* ADogNamedDog: Big isn't too creative with the names, as his frog friend is named Froggy.
* AirborneAircraftCarrier: The Egg Carrier [[spoiler:and the Egg Carrier 2]].
* AirVentPassageway: The game actually makes use of this trope a number of times in order to progress from level to level.
** For example, Sonic and Tails travel through the sewers of Casinopolis in order to find [[spoiler:the Chaos Emerald located there.]]
** This is also how Gamma and Amy choose to travel through the Hot Shelter in the Egg Carrier.
* AllThereInTheManual:
** According an official Sonic website, [=ZERO=] is the "zeroth" E-Series robot with the official designation of E-100 Alpha.
** Said website also states Chaos' origin as a Chao mutated from the Chaos Emeralds' energy.
** One of the game's official strategy guides gives names E-Series numbers to all of the game's badniks. Said guide also explains a little more of the ancient echidna's backstory, such as Pachacamac's war mongering being pivoted by his mother's death.
* AllIsWellThatEndsWell: At the end of the game, [[spoiler:as the characters are recuperating after their battle against Perfect Chaos, Tails invokes this trope verbatim, ignoring the fact that the city has been completely inundated and destroyed.]]
* AlmostOutOfOxygen: A staple of the franchise. That countdown music is unnerving.
* AlreadyDoneForYou: Given that the storylines (apart from the Super Sonic storyline) are done in a RashomonStyle, expect this to happen very often.
* AmusementPark: Twinkle Park.
* AnAesop: [[spoiler:WithGreatPowerComesGreatInsanity. The tragic story of the Echidna race and Chaos prove this.]]
* AndYourRewardIsClothes: [[spoiler:Getting all medals unlocks Metal Sonic, who is essentially a reskinned Sonic with slightly altered animations. You can only use him in Trial mode.]]
* AnimatedAdaptation: Was adapted into an arc in the AnimeOfTheGame ''Anime/SonicX''.
* AnotherSideAnotherStory: Play through the main story from 6 different perspectives. Each character also gets a piece of the backstory of Chaos and the echidna race, only by playing through all stories do you get the complete sequence.
** And any of the exact same scenes played in multiple stories get alternate dialogue, at least in English.
* ApocalypseHow: [[spoiler:Chaos' destruction of the echidna civilization 3000 years ago is a Class 1. Then Chaos' destruction of Station Square is a Class 0 since the citizens possibly survived.]]
* ArmedWithCanon: The localization team pokes fun at the "Robotnik" name debate just before the Egg Hornet battle. Dr. Robotnik throws a tantrum and insists on being addressed by his real name; everyone just ignores him and continues calling him Eggman.
* ArchetypalCharacter: While the game introduces story arcs and attempts character development at points, all of the characters are rather one dimensional and archetypal in their personalities, with their characterization seldom extending beyond their goals. Sonic is a snarky hero, Eggman is a dime a dozen shamelessly evil scientist, Tails is insecure and just wants to be recognized as a hero, Knuckles wants to save the shards of the Master Emerald he guards, Amy is a clingy wannabe girlfriend, Gamma is driven by a single-minded goal to destroy his fellow robots once he turns on Eggman, and Big is a lazy simpleton who just wants to find his pet frog and go home. Chaos is more of a vengeful force of nature than a fully realized character, not helped by his [[TheStoic lack of expressiveness]] and [[TheVoiceless voicelessness]], Tikal is a peace loving noble and her father is a ruthless warmonger.
* ArtEvolution: [=SA1=] introduced the art style for Sonic and friends that would be used in future games. Amy was the one affected most by this, as she no longer looks like [[DistaffCounterpart a pink Sonic in drag]]. However, the Sonic-themed pinball table in Sonic's version of Casinopolis ''does'' feature stock artwork from the earlier games.
* ArtificialStupidity:
** Tails' levels have you race against Sonic, who is technically another player controlled by an AI. Because of this, Sonic tends to struggle when dealing with obstacles (which is particularly notable at the end of Casinopolis, where he takes a very long time just to jump through a bunch of spikes), but he makes up for this by [[TheComputerIsACheatingBastard rubber-banding his way to the goal]]. The last race against Eggman averts this because he's not an AI at all, instead he just follows a straight path to the goal.
** The fights against the other playable characters in the game (such as Sonic vs Knuckles) aren't much better, as they simply charge at you and don't bother dodging your attacks. Because of this, each fight will usually last under twenty seconds.
* AscendedExtra: Amy, originally a minor semi-recurrer beforehand, gained a prominent playable role in this and many titles following it.
* {{Badass}}: Sonic. Thanks to the new 3D presentation, we now get to see him outrun a killer whale, run down a building, and even [[spoiler:take out a water god.]]
** Knuckles is a more prominent example. He does something cool in all his appearences.
** Don't forget Chaos, the first real villain that the trio had trouble defeating toghetter.
** E-102 Gamma to a lesser degree, a multi-mode sniper badnik who, after backing from killing Sonic point blank, strives to defeat and rescue his fellow KillerRobot bretheren.
* {{Balloonacy}}: A single balloon is all Amy needs to float away from [=ZERO=]'s grasp.
* BareYourMidriff: Tikal.
* BattleInTheRain: Sonic's first encounter with Chaos.
* BigBad: Eggman, of course.
* BigBadWannabe: [[spoiler:Eggman, who Chaos eventually turns on and absorbs the Emeralds.]]
* BiggerOnTheInside: The Hot Shelter and Sky Deck suggests that the Egg Carrier is this.
* BigNo: Pachacamac belts out one after [[spoiler: his conquest invites the wrath of a furious Emerald powered Chaos onto his tribe.]]
* BittersweetEnding:
** In Gamma's story, [[spoiler:Gamma dies after destroying his brothers to free the Flickies, but a Flicky of his own is free as well, setting up the ending in Amy's story.]]
** In Super Sonic's story, [[spoiler:Chaos is neutralized, but Station Square remains a floody mess.]]
* BlobMonster: Chaos, who's made of water.
* BondVillainStupidity: Early in Sonic and Tails story following Casinopolis, Eggman successfully ambushes them, sleep gassing them, and stealing their recently acquired Chaos Emerald. Rather than simply using a lethal gas to begin with, or killing them immediately afterwards, he leaves them alone to wake up unharmed the next morning.
* BookEnds: Knuckles's story begins and ends with him narrating how he was fated to stay forever on Angel Island guarding the Master Emerald. In the beginning, he mentions that he doesn't know why he was given this role in life, but in the end, he believes he is better off for that.
* BornAgainImmortality: The Chao can come back from death this way if raised correctly. In fact, dying and being reborn twice is one of the requirements for a Chao to become a perfectly immortal Chaos Chao.
* BossArenaIdiocy: The arena Amy fights [=ZERO=] in is enclosed by an electric fence. If you knock [=ZERO=] into the fence, it will reveal a button in its head. Hitting this button damages and ultimately self destructs it.
** Knuckles would not have defeated Chaos 6 if it weren't for the ice robots scattered all over the arena (for Sonic's fight with Chaos 6, see TacticalSuicideBoss below).
* BossRush: Beating a story unlocks a minigame where you fight each of the bosses faced in that story one after the other (the exception being [[spoiler:Super Sonic]], whose story ''only'' consists of a single boss fight with some Adventure Field navigation beforehand). Gamma's version is strangely restricted to only the Adventure Field battles against E-101 Beta [[spoiler:and E-101 Mark II]], lacking any of his in-level bosses.
* BossOnlyLevel: Outside of the three E-Series robots not named 101 in Gamma's story, all the boss fights and character duels are self-contained on the main adventure fields (though the last boss fights for Sonic and Tails start right after the player completes their final action stages, but are not directly connected to those stages outside of terrain.)
** [[spoiler:This is also what the final storyline regarding Super Sonic is. This storyline, which appears after everything else in the main story is completed, only has Sonic running to two plot locations in the Mystic Ruins, with the second, done by taking the cart into the back jungle, starts the long series of cutscenes and eventually the Perfect Chaos FinalBoss fight as Super Sonic, which is the only challenge in this storyline.]]
* BrokenBridge: Parts of the Mystic Ruins, including Angel Island itself, are blocked off by pedestals that require [[PlotCoupon magic stones]]. The same goes for Station Square, except that the keys are more mundane. Also, after the Tornado crashes, Sonic (who landed in Station Square) and Tails (who landed in the Mystic Ruins) can't reunite because the train isn't running since the workers have gone on strike.
* ButNowIMustGo: [[spoiler:Both Tikal and Chaos.]]
* CallBack:
** Icecap first appeared as "[=IceCap=] Zone" in ''Sonic the Hedgehog 3'', and it opened with a snowboarding segment, too. Red Mountain's inner section is also clearly part of Lava Reef from ''Sonic & Knuckles''. Both are set on Angel Island.
** After the Sky Deck minigame, Tails has a {{flashback}} to his first meeting with Sonic.
** Amy Rose has a {{flashback}} to her kidnapping in ''VideoGame/SonicTheHedgehogCD''.
%%* CameraScrew
* TheCameo:
** [=NiGHTS=], from ''[[VideoGame/NiGHTSIntoDreams NiGHTS into Dreams...]]'', has his own pinball board in Casinopolis and will even appear in person sometimes.
** [[VideoGame/SonicTheHedgehogCD Metal Sonic]] and [[VideoGame/SonicTheHedgehog2 Mecha]] [[VideoGame/Sonic3AndKnuckles Sonic]] appear in stasis tubes at Eggman's Mystic Ruins base.
** [[VideoGame/SonicR Tails Doll]] (along with doll versions of Knuckles and Sonic) appear as training dummies in Gamma's first level.
** In the ''DX: Director's Cut'' version, Cream the Rabbit appears at certain points in the Adventure Field.
** Chris Thorndyke from "Anime/SonicX" will appear as a billboard in certain missions.
* CannotSpitItOut: A ShrinkingViolet in Station Square has a major crush on the guy who works the counter at the Burger Shop. She can't muster up the courage to tell him how she feels, so, she ends up hanging around the stop all day, not saying anything. From his vantage point, she's a StalkerWithACrush. Towards the end of the entire game's storyline, she figures out a way to overcome her problem: get a job at the Burger Shop alongside her object of affection.
* CaptainObvious: Quite a few snarky moments in [=SA1=], if you look closely.
-->''(the Egg Carrier changes its shape)''\\
'''Tails:''' Ahhh, wow! It's changed shape. Did you see that?\\
''(Sonic gives him a weary look, and ignores him)''\\
'''Sonic:''' Darn! This makes it harder for us to get to the bridge! \\
'''Tails''': [[LampshadeHanging I hate it when he doesn't listen...]]
** Also, Gamma, due to being a robot. It states:
--> '''Gamma''' (when transported into the past via a vision): "This presents a problem."\\
'''Gamma''' (after seeing what happened to Beta after defeating him at the beginning): "This is the wrong room."
* CasinoPark: Casinopolis.
* ChaosArchitecture: Angel Island looks virtually nothing like it did in ''[[VideoGame/Sonic3AndKnuckles Sonic 3 & Knuckles]]''. Here is [[http://fc09.deviantart.net/fs71/f/2010/045/b/c/Angel_Island_for_Sonic_FGX_by_Sonicman98.gif the original]], contrasted to [[http://images.wikia.com/sonic/images/8/8e/SA_Angel_Island_2.jpg this counterpart.]]
* CerebusSyndrome: This was the first game in the franchise where the tone started to move on from a cartoon tone to a darker, shonen-anime esque tone. The real antagonist, Chaos, isn't a standard "take over the world" bad guy, but a vengeful, mourning creature of god-like power who wiped out an entire civilization (and this is also the first game in the series where characters are explicitly killed, albeit off-screen). The stakes are raised much higher here than in any of the previous entries.
* CharacterDevelopment:
** Tails learns to take on troubles without Sonic's help, and he even musters the courage to stop Eggman's attack on Station Square.
** Amy goes from being a DamselInDistress depending on Sonic to save her to an ActionGirl beating up the very robot that constantly pursued her.
** E-102 Gamma learns about love and caring, which motivates it to stop being a mindless servant to Eggman, go on its own mission, and [[spoiler:eventually has to die to free the bird trapped inside of him]].
* CharacterizationMarchesOn: This game marks the first time Knuckles is portrayed as stoic and serious in contrast to his debut in ''[[VideoGame/Sonic3AndKnuckles Sonic 3 & Knuckles]]'' where he was constantly laughing at you when he activated one of his traps.
-->"Unlike Sonic, I don't chuckle. I'd rather flex my muscles!"
-->--"Unknown From M.E.", theme of Knuckles
* ChekhovsGun: The Chaos Emerald inside the Tornado 2. It plays a major role in setting off the events for the Super Sonic chapter.
* ChildProdigy: Tails was implied to have this in previous games, but this is probably the first major series game [[note]]''VideoGame/TailsAdventure'' and ''VideoGame/SonicTheFighters'', minor spinoff games, notwithstanding[[/note]]which shows the full extent of his technical skills, such as his mechanically powered house and his transforming airplane.
* ClimaxBoss: Several for different character modes, mostly aligned to their CharacterDevelopment:
** The Egg Walker is the FinalBoss of Tails' mode, culminating in him developing independence from Sonic and stopping Eggman on his own.
** The Sonic/Tails vs E-102 Gamma boss. While pathetically easy whoever you play as, it occurs just after [[spoiler: Gamma's PetTheDog moment releasing Amy from an unknowing Eggman, leading Amy to break up the fight and provoke his HeelFaceTurn.]]
** Also E-101 Beta Mk II, Gamma's FinalBoss, happening straight after Gamma establishes his ForegoneConclusion that [[spoiler: he will sacrifice himself to complete his E-Series rescue mission.]]
* ComicBookAdaptation: Was adapted in story arcs in ''ComicBook/ArchieComicsSonicTheHedgehog'' and also as what was notably the last new story arc in ''ComicBook/SonicTheComic''.
* TheComputerIsACheatingBastard: Present in Tails's stages, specifically of the RubberBandAI variety.
** More infamous is [[SpellMyNameWithAnS Chaclon/Chacron]], a Chao that shows up in the Chao Races upon their completion. What makes him a cheater is that he's constantly in the "boost" state and runs right past the tree he's supposed to shake.
* ConsoleCameo: E105ζ (E-105 Zeta) is made of six Dreamcasts [[http://info.sonicretro.org/File:E105.png located around the grey blocks under his cannons.]]
* ContinuityNod:
-->'''Sonic (to Knuckles):''' "[[VideoGame/Sonic3AndKnuckles Did Eggman trick you ]]''[[VideoGame/Sonic3AndKnuckles again]]''?"
** The music for Twinkle Park's hovercraft and Windy Valley's "The Air" segments are remixes of the Panic Puppet and Green Grove themes from ''Sonic3DFlickiesIsland''. Also, the second part of Emerald Coast has a MusicalNod to the first boss theme from that game.
** One of Amy's fantasies is of Sonic saving her in ''VideoGame/SonicTheHedgehogCD''. However, [[SuddenlyBlonde the models weren't changed]].
** When playing other characters' stories, your allies will sport any power-up accessories you picked up for them in their stories.
** After getting their powers drained by Perfect Chaos, the Chaos Emeralds look the same as the Super Emeralds looked like in ''[[VideoGame/Sonic3AndKnuckles Sonic 3 & Knuckles]]'' in their powerless state (except for the size, of course), prior to being fully restored by the player.
** The ending to Sonic's story mode is more or less a 3D tribute to the ending of ''{{VideoGame/SonicTheHedgehog}}'', complete with Sonic's YeahShot into the camera.
* ConvectionSchmonvection: Sonic and Gamma can survive just fine in the incredibly hot volcano section of Red Mountain, with lava and geysers being the only hazards that damage them. Then again, this is true of all ''Sonic'' games where the characters don't suffer any ill effects from standing only a few inches above a lava pit.
* CrazyPrepared: Eggman. Not only does he have the God of Destruction at his command, he has a giant flying carrier (although it functions more like a battleship), [[spoiler:a second carrier to use against Chaos if it goes rogue, a HUGE missile stationed off the coast of Station Square should the Egg Carrier and Chaos be defeated]], and a giant base in the middle of Mystic Ruins.
* CreatureBreedingMechanic: Both games include Chao gardens. Chao may be trained and any two may be crossed, with the usual [[LamarckWasRight Lamarckian]] mechanics coming into play. This doesn't affect anything outside of the garden, though.
* CriticalExistenceFailure: As in most games in the franchise, Sonic and the cast can take any amount of damage, from a barrage of Eggman's launched missiles to an explosion a third the size of the Egg Carrier, without any outward sign of injury, but after their last ring is lost, brushing against a robot chimp is enough for a K.O.
* CrystalPrison: The Master Emerald is this to Chaos.
* CurbStompBattle: In the final route of the game, [[spoiler:Eggman hops into the Egg Carrier 2 to tame Perfect Chaos. It's on-screen for maybe ten seconds before Perfect Chaos blows it up.]]
** The Sonic/Tails vs Gamma battles usually play the outcome as such, depending on which character is playing. In Amy's case, Sonic is winning, but with Gamma still holding ground.
* CutsceneIncompetence: In some cutscenes, Sonic is just standing there.
** He also seems to forget how to run and ends up walking to close distance when he ''needs'' to run to prevent something bad from happening.
* CutscenePowerToTheMax:
** Now we know why Sonic refuses to sit in the cockpit of Tails' plane -- because gravity means '''nothing''' to him. He survives falling several kilometers to the ground not once, but ''twice'' in the game. The second time, Sonic's body endures a comical pancake effect when he hits the ground, but he's no worse for wear.
** In Tails' ending, he manages to fly all the way from Station Square to the Mystic Ruins without getting tired.
* DarkerAndEdgier: At least in comparison to most ''Sonic'' games released before it. This game literally starts off with its opening cutscene depicting a city being flooded by Perfect Chaos, and later in the game, [[spoiler:the echidna tribe kill the Chao]].
** Gamma's story is this to the rest of the game, complete with an explicitly BittersweetEnding. Super Sonic's story has a somewhat grimmer tone than the rest of the game as well.
* DeadlyRotaryFan: Spinner and Thunder Spinner are fitted with these. Speed Highway also features a HelicopterBlender obstacle.
* DenserAndWackier: Big's story is much more offbeat and light hearted compared to most of the other character modes.
* DeusExMachina: The Chaos Emeralds (or at least the abilities they grant) work as this. While its clear they had magical abilities from the start, the nature of their power is only vaguely explained throughout the story, and the idea of their powers having both negative and positive energy, with the use of either depending on the alignment of a character, is only brought up very late in the story, making the transformation of a character like Sonic into Super Sonic with them come off as rather out of the blue, especially for someone who isn't familiar with their use in previous entries in the series.
* TheDevTeamThinksOfEverything:
** When Big enters the sewer elevator, his model is large enough that the door overlaps onto his tail. prompting a sound clip of a door shut and a deadpan "Ow" from Big.
** An unused cutscene exists inside the game's memory for if Gamma quit or lost the Final Egg practice course, where Eggman would scold Gamma and tell him to get back to training. Averted since [[DummiedOut the cutscene was not implemented into the gameplay itself.]]
* DidYouJustPunchOutCthulhu : The final battle against [[spoiler:Perfect Chaos]].
* DigAttack: Knuckles can dig underground once he finds the shovel claws upgrade. This is mostly used to find Master Emerald pieces that are buried underground. ''VideoGame/SonicBattle'' takes this one step further by having Knuckles' burrow ability as a special move, in which after he goes underground, he can move under an enemy and pop up from below to his or her surprise.
* DidntThinkThisThrough: Tails modifies his plane so he and Sonic can fly up to the Egg Carrier. This seems to go smoothly until Tails realizes he forgot to equip landing gear ''just as they're about to land the plane''.
* DoingInTheWizard: In-game, Chaos is consistently portrayed as being some kind of genuine deity that the echidnas worshiped, and having some unexplained connection to the Chaos Emeralds and the Chao--where exactly he came from is never explained in the story. Out of universe, Sonic Channel's profile of the character claims that he is just a Chao mutated by the energy of the Chaos Emeralds.
* DoubleKnockout:
** This happens after the Sonic (or Tails) vs Knuckles fight, both characters run up to each other to attack, only to knock each other to the ground, followed with Sonic or Tails dropping the two Chaos Emeralds.
** This can happen in the end of the Egg Viper boss battle, in which it specifically [[TakingYouWithMe tries to take Sonic down with it.]]
* DownloadableContent: Sega released a lot of this, which a player could download onto their [=VMUs=] (Visual Memory Unit). You could [[https://www.youtube.com/watch?v=LOxuMgwYwMs celebrate Christmas]] or [[https://www.youtube.com/watch?v=0s5zetlnnVM the year 2000]], in addition to [[https://www.youtube.com/watch?v=gXecwRD0l4Q the launch of the Dreamcast in the United States]], or [[https://www.youtube.com/watch?v=KrVsGtnpOXo try to win sportswear from Reebok]].
* TheDragon: Chaos to Eggman. [[spoiler:[[DragonWithAnAgenda If just to get the Emeralds.]]]] E-102 Gamma's role in preserving him and helping against the heroes [[spoiler:prior to a HeelFaceTurn]] may apply them as CoDragons.
* DragonWithAnAgenda: Chaos only helps Eggman to get the Emeralds so that [[spoiler:Chaos can go OneWingedAngel and destroy the world]].
* DreamSequence: The visions of the echidnas' ancient history work as this.
* DubNameChange: Not unlike ''Super Mario 64'', this game marks the transition from a dub name to the original name and does so by using both, in this case Dr. Robotnik and Dr. Eggman.
** Outside of the obvious turning point for the series villain, a few minor elements were renamed when the game went International, such as Mystic Ruin to Mystic Ruins and Spina to Spinner.
* DuelingPlayerCharacters: The game has Sonic and Knuckles fight again, as well as E-102 Gamma. However, playing through as Knuckles and Gamma allows the player to fight Sonic, and playing as Tails puts him in the fights instead of Sonic.
* DullSurprise: Due to technical limitations of the CGI, all of the characters have very blank or basic expressions and rigid to nonexistent body language. [[https://www.youtube.com/watch?v=demZZpIWMyA And then there's Knuckles' absolutely apathetic "oh no" whenever Sonic hits him during their fight.]]
* DummiedOut: The game is visibly an ObviousBeta, but aside from the obvious rough edges, some unused textures, music and sprites exist inside the game, at least one unused cutscene (see above), and data listing at least three unmade levels. The DX remake also has a lot of the options and extras from the original's online mode inside it's memory that can be accessed via hacking, such as the extra Twinkle Circuit mini games.
* EarnYourHappyEnding: All six character stories, [[spoiler: though it's rather bittersweet in Gamma's case]].
* EasterEgg: Cream the Rabbit [[EarlyBirdCameo makes a short appearance]] in the remake. [[http://www.youtube.com/watch?v=wexxG6IaNi4&feature=related See video here.]]
** This one should take a couple minutes to get to - a hidden [[http://www.youtube.com/watch?v=NBtkugzC6Uo room]]
* EggshellClothing: Chao can wear eggshells on their heads.
* EldritchAbomination: Chaos, a slime creature whose innards can be seen through it. They get more mechanical as he absorbs more Emeralds, until his final form.
* EleventhHourSuperpower: Super Sonic, at the very end.
* EliteMook: The E-100 Series robots were designed by Eggman to be more more intelligent and dangerous than his normal Badniks. E-102 Gamma can challenge Sonic just on his own, and in his own story comes seconds from defeating him outright.
* EternalEngine: Final Egg.
* EvilIsNotAToy: [[spoiler:Chaos is only using Eggman so he can destroy the world with the power of the Chaos Emeralds.]]
* ExpositionFairy: Tikal is always there to guide the player.
* {{Expy}}: Twinkle Park is one for Sega's "Sega-World" amusement park.
* FailedASpotCheck: While it's not acknowledged by the characters themselves, Sonic is shocked to hear from Tails that Angel Island has fallen again during the Super Sonic story, despite the fact that he is lying down in view of where it fell.
* {{Fanfare}}: While addressing his robots, Eggman plays his own [[http://www.youtube.com/watch?v=fg3ezY6aDV4 canned fanfare music]]. Pretty amusing.
* FantasyKitchenSink: A superpowered deity, abandoned civilizations, fantasy magic, ghosts, time travel and talking animals are all present in the game, with some science fiction elements and even a [[WhatMeasureIsANonHuman "Ghost in the Machine" story]] for one of the major characters sandwiched in.
* {{Filler}}:
** Big the Cat's plot has almost no bearing on the rest of the games storyline. The only thing that ties him into it is because his pet frog is hosting and emerald and some essence of Chaos.
** Similarly Amy's plot is only tied in via the one emerald her Birdie is holding (which is stolen halfway in) and her pivoting E-102 Gamma's HeelFaceTurn, which ironically ends his own relevance to the central story.
* FiveRoundsRapid: The cops unloading their clips at Chaos 0.
** OH NO! OUR WEAPONS ARE USELESS!
* FixedCamera: Made more adjustable in the ''DX'' version.
* FlawExploitation: Eggman, once again, tricks Knuckles into fighting Sonic as a way to nab two Chaos Emeralds. To a lesser degree, the first Emerald is nabbed from an opening when Sonic and Tails get cocky post battle.
* FloatingContinent: Angel Island before the Master Emerald was shattered, and Windy Valley.
* {{Foreshadowing}}: The fact that Tikal had actually managed to send Gamma's mental mind to the past foreshadows him [[spoiler:becoming sentient]] in his chapter.
** At the start of Knuckles' story, when the Master Emerald is broken, you can see a Hint Ball (in other words, Tikal's spirit) fly out of it.
* ForTheEvulz: This is about the extent of Eggman's characterization in the game--his only goal is to destroy Station Square so he can build his own evil amusement park, Eggmanland (Robotnikland in the English dub), over its ruins.
* FourLinesAllWaiting: Six main character storylines that both run alongside and intertwine with each other, with one overarching storyline that most of them loosely tie into (a vengeful monster has been released by the main villain, and is secretly pulling strings to eventually destroy the world).
* FreeRotatingCamera: Not universal though.
* FreudianExcuse: [[spoiler:Pachacamac [[RetCon retroactively]] gets one through ''VideoGame/SonicChronicles'', which reveals that his clan were fighting a losing war against the technologically superior Nocturnus and claiming the Emeralds was a desperate attempt to turn the tides.]]
* {{Friendly Playful Dolphin}}s: Dolphins jump around you in Sonic's first stage, "Emerald Coast", if you're looking in right place at the right time. The appearance of these dolphins and their numbers seems to be performance based, or it might be random.
* TheFriendsWhoNeverHang: Only Sonic and Tails interact with all five other characters in the story, with Knuckles, Amy, Big and Gamma never really meeting one or two. They can still occasionally find them as generic NPCs to assist in unlocking them however.
* {{Futureshadowing}}: Some of the visions of the past do this. No, seriously.
* GameBreakingBug:
** Windows will crash in certain times in ''DX'', most commonly during the fight with the Egg Hornet.
** Don't even think about turning off or resetting the system while saving.
* GameplayAndStoryIntegration: In the Chao Gardens, Chao have ResurrectiveImmortality as long as they're properly cared for. In the story, [[spoiler:the Chao who were Chaos' friends kept living through the generations until they were able to meet up with him again in the ending.]]
** At the end of Sky Chase Act 1, Tails and Sonic are shot down. If you die during Sky Chase Act 2, Sonic will shout "[[HereWeGoAgain Not again!]]" as they're going down.
* GameplayRoulette: ''Sonic Adventure'' was where all of the {{Unexpected Gameplay Change}}s the ''Sonic'' series became infamous for started.
* GenreShift: The previous games in the series were surrealistic cartoon platformers with science fiction elements. This game shifts the tone of the series to a shonen anime fantasy adventure, and cranking up the science fiction and magical elements far more.
* GimmickLevel: Sonic's version of Casinopolis has a Chaos Emerald inside of a large vault, on a platform that's too high for Sonic to jump onto. To reach the Emerald you need to fill up the vault with 400 rings so the floor is high enough to jump off of, and to get the rings you need to play pinball (with Sonic as the ball) instead of platforming.
* GoingThroughTheMotions: Not a major example, but quite noticeable in Amy's ending when she performs her boss victory animation and then abruptly snaps back to her standing animation.
* GoThroughMe:
** In the {{backstory}}, Tikal tries to defend the Chao and the Chaos Emeralds from her dad and his soldiers. Said soldiers brusquely push her aside and proceed to incur Chaos' wrath.
** In the aftermath of Sonic's (or Tails') fight with Gamma, [[TheRashomon regardless of who wins]], Amy intervenes to convince the victor to let the other live.
* GratuitousEnglish: Sonic in the Japanese dub sometimes speaks English with a [[JapaneseRanguage thick accent]], such as when he tells players to "Serect yo kaakta!"
* GravityScrew: Most notably in Lost World, where panels on the wall glow when orientated correctly by hitting a switch, allowing Sonic and Knuckles to simply walk up the wall. The last part of Sky Deck changes orientation as well, and Knuckles can actually control this.
* HallOfMirrors: A segment exclusive to Amy's version of Twinkle Park.
* HeroicSacrifice: [[spoiler:Before the events of ''Sonic Adventure'', in order to save the world from Chaos' destruction, Tikal sealed him, along with herself, in the Master Emerald.]]
* HijackedByGanon: Inverted by [[spoiler:Chaos taking over the role of central villain from Eggman in the final story.]]
* HintsAreForLosers: Touching one Hint Orb in Knuckles' B Rank missions disqualifies you from getting the Emblem.
* HongKongDub: The lipsyncing is just plain bizarre and off a lot of the time.
* HopeSpot: Zig-zagged at the end of Amy's story. Birdie is reunited with his family, and everything seems okay... [[spoiler:then suddenly ZERO shows up and swats Birdie out of the sky. After ZERO's defeat, Birdie wakes up and is seemingly okay, but as he flies off, he suddenly rapidly drops from sight... only to soar triumphantly back into view and fly off with his family in tow]].
* HubLevel: Station Square, Mystic Ruins, and the Egg Carrier.
* HundredPercentCompletion: Getting all of the emblems entails beating the action stages again, under more challenging circumstances. At most, you have to:
** Sonic: Finish each action stage within an allotted timeframe.
** Tails: Beat Sonic or Eggman again (they're faster).
** Knuckles: Same as Sonic, only the allotted time is one to two minutes.
** Amy: Same as Sonic.
** Big: Catch a fish weighing in at 2000 grams and catch Froggy.
** Gamma: Reach and dispose of a particular target within a certain amount of time left on the clock.
* ICannotSelfTerminate: Played with during Gamma's story. Gamma is perfectly capable of self-terminating, it's just that up until the penultimate boss Gamma doesn't realize that his self-given mission technically ''requires him to kill himself''. The moment of contemplation concerning his mortality that he has when he realizes this is almost heart-breaking despite almost no dialogue or music being present in the scene. He ends up averting this trope and allows himself to die from his injuries so that the Flicky inside of him can be freed.
* ICantBelieveImSayingThis: Knuckles says this, agreeing with Tails that Sonic is the only one who can harness the true power of the Chaos Emeralds after Perfect Chaos absorbed their negative energy.
* IOweYouMyLife: Not directly stated, but E-102 Gamma's resolve to rescue the animals trapped inside the E-Series robots was partly due to Amy saving its life.
** Said act by Amy was also provoked by Gamma freeing her and Birdie from Eggman's cell inside the Egg Carrier (which would later crash land into the ocean) making it both issued and returned at the same time.
* ISOStandardUrbanGroceries: The brown paper bag Amy carries in the introductory cutscene to her story.
* IWantSong: Tails's and Amy's themes: ''[[IJustWantToBeSpecial Believe in Myself]]'' and ''[[StalkerWithACrush My Sweet Passion]]''.
* IdiotBall: All three incidents when Sonic and Tails lose Chaos Emeralds to Eggman. The third time this occurs, when two Chaos Emeralds are knocked out of Sonic/Tails's {{Hammerspace}} (depending on what character you're being) by a sharp impact. He then proceeds to '''lie there''' while Eggman lazily floats over and [[TractorBeam beams them up]].
* IgnorantOfTheCall: Most of the cast react this way to Tikal's flashbacks. Near the end of his story Sonic fails to get the message that he should go after Chaos instead of Eggman.
* ImplausibleDeniability: Knuckles seems to pull this off after Sonic asked him if he got tricked by Eggman again. This quote from Knuckles' story sums it up:
-->"Like, you weren't?"
* InCaseOfBossFightBreakGlass: The Egg Viper, but it gets harder as you go on.
* IncomingHam: Eggman, Eggman, Eggman.
-->"YOUUUUUUUUUUU KNOOWWWWWWWWWW NOTHING, [[YouFOOL FOOOOOOOOOOOOL!]] It's ''CHAOS! The GOD! OF DESTRUCTION!! [[EvilLaugh HAHAHAHAHAHAHAHAHAHAHA!]]''"
* IndyEscape: At various points in Sonic's storyline, he has to evade the jaws of an angered orca, an avalanche and an ''Franchise/IndianaJones''-esque flaming boulder.
* InsultBackfire: Sonic calls Robotnik "Eggman", and he protests that his name is Ivo Robotnik. Wait, what does he call himself nowadays?
* InsurmountableWaistHighFence: Right towards the end of Twinkle Park for Sonic, there's an iron gate blocking you from getting to a spring if you end up on the right side of it. You can barely jump higher than it by yourself and you can definitely jump higher than it if you get up some speed with a Spin Dash. However, the game won't let you pass it from that side, you have to circumnavigate the entire circular roof to approach the spring from the other side.[[note]]However, unlike other examples, this CAN be circumvented by simply jumping at the spring from one of the floating platforms leading to the roof. If you execute a homing attack at it, the game won't block your progress, which is good for the Emblem.[[/note]]
* KaizoTrap: Egg Viper. The camera angle isn't great either, so even if you know his suicide attack is coming, you won't be able to tell where he's gonna hit so you may still die anyway. And beware of losing too many platforms, because the Viper will take you down if it's the last platform remaining. Cue rage.
* KarmaHoudini: [[spoiler: Chaos suffers a few beatdowns, but his HappyEnding can be considered a bit spurious considering his rampage likely killed hundreds to thousands of people.]]
* KarmicDeath: Implied. Chaos absorbs the Emeralds to transform into Perfect Chaos, wiping out Pachacamac and the echidnas for all of their actions towards Tikal and the Chao.
* KickTheDog: Eggman does it a ''lot'' in this game. He's portrayed as a lot more evil here than in most portrayals.
** In the flashback of the final story, Pachacamac ordered the echidna warriors to charge to the Emerald shrine, in which they trampled Tikal and injured the Chao, just so they can seize the Chaos Emeralds. Chaos didn't take kindly of this.
* KnightOfCerebus: Chaos. He is the first major threat Sonic and co. face that has ''no'' humorous quirks or traits whatsoever in persona and design; while his threat is genuine, he isn't seen as much more than a [[TheDragon Dragon]] to Eggman [[spoiler:until the climax and finale, when things truly take a turn for the worse when he finally turns on Eggman and gets all of the Emeralds.]]
* LastBreathBullet: The defeated E-101 mk.II gets in one last shot at Gamma before exploding; the shot fatally wounds Gamma and he too is destroyed shortly after.
* LastNoteNightmare: "Fakery way" for Twinkle Park starts out in a quiet, cute tone, but slowly becomes much more creepy and menacing.
* LastOfHisKind: Knuckles is the only echidna alive. [[spoiler:Though Tikal's spirit lingers around after being released from inside the Master Emerald.]]
* {{Leitmotif}}: Every character is accompanied by their theme tune when they appear.
* LensFlare: Present in some of the cutscenes, as well as Emerald Coast and Sky Chase Act I.
* LethalLavaLand: Red Mountain, [[HailfirePeaks combined with]] some DeathMountain.
* LetsYouAndHimFight: Eggman tricks Knuckles into fighting Sonic for the second time (or Tails if you play as him).
* LevelsTakeFlight: Sky Chase reappears with two acts, and allows Tails to actually fire upon incoming enemies with his Tornado.
* LongSongShortScene: A few jingles and themes were unused in gameplay or for purposes different from how they are labelled (eg. "Calm After The Storm" is labelled as the theme for the crashed Egg Carrier Adventure Field in the Sound Test, but is used only in a short cutscene in Gamma's story). Many tunes were also truncated and can only be heard in full in the games' official soundtrack.
* MacguffinDeliveryService: Sonic and friends do a ''terrible'' job of keeping the Chaos Emeralds away from Eggman and Chaos.
* MalevolentArchitecture: Speed Highway, a highway that uses loop-de-loops, corkscrews and ''has gaps missing'', all while being high in the air.
* MaliciousMisnaming: Sonic calls Knuckles a "Knucklehead" for the first time.
* MamaBear: Amy to Birdie. In one instance, she adamantly refuses to give Birdie to Gamma, which then led to his change of heart. In the other instance which stands out more, Amy was [[BerserkButton enraged when [=ZERO=] knocks Birdie out cold]] and was very keen on bashing him with her hammer.
* MinionWithAnFInEvil: E-102 Gamma ultimately.
* MyGodWhatHaveIDone: E-102 Gamma states this in his story recap following releasing Amy and Birdie and disobeying his master's orders.
* MythologyGag:
** [[WesternAnimation/AdventuresOfSonicTheHedgehog "Ooh, I hate that Sonic!"]]
** The invincibility music quotes [[VideoGame/SonicTheHedgehogCD "Toot Toot Sonic Warrior"]] at one point.
* NiceJobBreakingItHero: Knuckles being tricked into fighting Sonic led the two colliding with each other. As a result, Sonic fumbles the two remaining Chaos Emeralds (one of them being green which Knuckles ''thought was a piece of the Master Emerald''), only for Eggman to steal them and power up Chaos into his fourth form. As Sonic best puts it:
-->'''Sonic''': Smooth move, [[JustForPun knucklehead]]!
* NiceJobFixingItVillain:
** Sonic does not have a way to defeat Chaos 6, but luckily Eggman keeps dropping ice-spewing egg robots onto the battlefield that Sonic can use to freeze Chaos and hit him.
** E-101 Mark II fires one last shot at Gamma before exploding, killing them both and releasing their Flickies.
** Eggman's mistreatment of the E-Series and Amy played part in E-102 Gamma's HeelFaceTurn. In Gamma's own story at least, had this not occurred, he would have destroyed Sonic for him.
* NobodyPoops: Surprisingly averted. One Action Stage (Hot Shelter) contains men's and women's restrooms, both of which can be entered, though not used.
* NoOSHACompliance: Station Square is a death trap, boasting a highway with loops and a pleasure park containing floating platforms and a hall of mirrors where the flooring tends to give way beneath you.
** Angel Island's altar is only accessible by a narrow bridge with no handrail over a bottomless chasm.
** Eggman would be in trouble if a safety inspector took a good look at the Egg Carrier's Sky Deck.
* NonIndicativeName: Some of the levels as other characters, who only play in certain parts of them:
** Casinopolis as Tails takes place entirely in the sewers.
** Speed Highway as Knuckles features essentially none of the highways and much less speed, due to being an emerald hunting stage at the bottom streets of the city.
** Gamma's Final Egg is his ''first'' level.
* ObviousBeta: The game was rushed for its original Japanese release and was loaded with glitches, forcing Sonic Team to delay the U.S. release by a year to patch it up. Even then, the game still has loads of glitches, so it's very easy to break wide open, most notably in the DX port, which adds even more glitches than the original Dreamcast game. [[http://www.gamefaqs.com/pc/624155-sonic-adventure-dx-directors-cut-2011/faqs/26151 This page]] gives many examples of them.
* OffscreenMomentOfAwesome: Somehow Big managed to fly Tails' highly advanced Tornado plane back to his home with zero experience. Sadly we see about a second of him taking off from the Egg Carrier. No Sky Chase minigame for you, Big.
* OffscreenTeleportation: [=ZERO=] in Amy's levels.
* OffscreenVillainDarkMatter: Eggman was somehow able to build a ''second'', fully functional Egg Carrier right alongside the original, just in time before the final battle.
* OhNoNotAgain: Knuckles says this when he is sent in a flashback in the past for the third time. Also, Sonic says this in his story after encountering Chaos, who has transformed into his 6th form.
* OneWingedAngel: Chaos becomes Perfect Chaos after he drains the negative energy out of the Chaos Emeralds.
* OutsideContextVillain: In almost all of the previous Sonic games, the threat always came from Eggman and his machines. Chaos is the first major villain in the series to rely entirely on mystical powers instead of the threat of science and machinery.[[note]]The sole exception in the earlier games was Witchcart, a [[VillainOfTheWeek throwaway villain]] from ''VideoGame/TailsSkypatrol'' who could trap people in crystals.[[/note]]
* PalmtreePanic: Emerald Coast.
* PalsWithJesus: Tikal and Chaos, God of Destruction.
* PantyShot: Amy belts one out in most of the cutscenes she's in, most prominently when you choose her in the character select screen. This is made unsettling by the fact that she's [[{{Lolicon}} only 12]]. [[FurryConfusion And a hedgehog]].
* PapaWolf: Chaos to Tikal and the Chao, as the echidnas learned the hard way.
* PathOfGreatestResistance: Ever since ''Sonic Adventure'' introduced the Homing Attack, nearly all ''Sonic'' games since then have had paths identifiable (and accessible) only by finding a trail of stationary midair enemies. This is most commonly used to begin an expert path or for a shortcut; very rarely is it actually required.
* PinballZone: Sonic's version of Casinopolis features Sonic and {{NiGHTS}}-[[ShoutOut themed]] pinball tables. Naturally, ''Sonic'' is the pinball.
* PlotCoupon: The Chaos Emeralds and finding them is the main focus of the story for both the heroes and the villain.
* PoliceAreUseless: Station Square's police force tries to shoot Chaos 0 but he absorbs all their bullets. Upon discovering this, they immediately retreat.
* PolygonCeiling - Most noticeably, the camera is spastic in its ''best'' moments, and aspects of the game such as the overworld and mini-games are far less polished than the stages proper.
* PooledFunds: Averted; Sonic builds a pile of 400 rings in Casinopolis so he can walk on it to get the Emerald.
* PoorCommunicationKills: Rather than talk to Sonic about why he's after the Master Emerald shards, Knuckles instead immediately starts a fight with Sonic and Tails without reasonably asking the two directly about it, which could have prevented the whole fight in the first place.
* ThePowerOfFriendship: The bond of Sonic with his TrueCompanions allows him to unlock the full potential of Super Sonic with the Chaos Emeralds, although Tails does say that Chaos only absorbed the negative energy of the Emeralds.
* ThePowerOfLove: The song playing through this, "Open Your Heart", also suggests it works as this.
* RaisingSim: The Chao Garden, which can still be done even when the main story is completed.
* RashomonStyle: Who won in the character vs. character fights? It depends who you ask. Most of the dialogue was re-recorded for each story even when it doesn't need to be.
** In Sonic and Tails's stories, the character played as is the one who fights most of the bosses and puts the keys in the Mystic Ruins.
* RidiculouslyCuteCritter: This game introduced Chao to the series.
* TheRuinsICaused: [[spoiler:The team looking down upon the flooded Station Square post-Chaos.]]
* RuleOfThree: Tails' and Knuckles' stories has three bosses, Knuckles gets a vision of the past on three separate occasions (whereas the other five characters only get one), and Amy's storyline has three levels (the fewest level count any character has in this game).
* {{Sampling}}: [[http://www.youtube.com/watch?v=K4FLexYgadg "Red Hot Skull"]], the theme that plays in the underground section in Red Mountain, samples its drumbeat from a Hip-Hop remix of "Ghetto Red Hot" by Super Cat (the [[http://www.youtube.com/watch?v=s98VjXtBSvo instrumental version]], to be exact).
* SceneryPorn: It may look a bit dated now, but it was considered highly impressive back then.
* SealedEvilInACan: Chaos [[spoiler:was originally sealed in the Master Emerald along with Tikal when he was about to destroy the world, but in modern times, Eggman freed him by destroying the Master Emerald. Subverted however that, when it turns out Chaos isn't actually evil, just very angry and vengeful.]]
* SealedGoodInACan: [[spoiler:Tikal, technically.]]
* SelfDeprecation: Big surprisingly has a subtle bit of this near the end of his game, supposing that if he must help Froggy on his own since no one would be bothered in rescuing ''him''. Naturally this happens just prior to Sonic offering a team up to save his friend.
* SelfServingMemory: While it's not mentioned in the game itself, the official strategy guide gives this as the reason for any differences between the character's stories.
* ShoutOut:
** [[NightsIntoDreams NiGHTS]] appears in the backgrounds, and the "flying" Chao is shaped like him.
** A section of Lost World has you [[Film/RaidersOfTheLostArk being chased by a boulder]].
** At one point, Gamma says "[[Franchise/StarTrek Resistance is futile.]]"
** Amy's intro cutscene has a bag marked "YU-2 Mart". YU-2 was what Yuji Naka was credited as in the Genesis Sonic games.
* ShowerScene: Possible in Casinopolis with Sonic if you have him stand under a showerhead, whereupon he'll start scrubbing himself. Knuckles can also trigger the water spray, but he has no custom animation for it.
* SlippySlideyIceWorld: Icecap, with an IcePalace section.
* SmokeOut: Eggman employs a variety of these tricks, including a flash grenade and sleeping gas.
* SpaceWhaleAesop: Using the good power of magical jewels will give you the superpower to beat up an vengeful deity and make him good again, or at least wise up to what a jerk he was.
* SpinAttack: Tails can swipe his tails as an attack, which is upgraded to infinite spinning with the Rhythm Badge. Amy can do the Spin Hammer Attack and swing her hammer while spinning, but she can't move while spinning.
* SpoilerOpening: The opening cinematic contains the destruction of Station Square and Chaos's final transformation. Since this is the first ''Sonic'' game with an unlockable secret finale, it may have been intentional to prevent players from putting the game down after completing Sonic's story. Or just to get some extra mileage out of the lengthy FMV sequence.
* StockVideoGamePuzzle: Quite a few different puzzles appear at varying points across the levels and characters, notably in Lost World.
* StuffBlowingUp: Sky Deck is full of cannons and explosions. Twinkle Park also features barrels that, once attacked, explode on a timer.
* SuddenNameChange: The Floating Island suddenly changed to Angel Island as of this game; Angel Island Zone was the name of the first level of ''[[VideoGame/Sonic3AndKnuckles Sonic 3 & Knuckles]]'', but it wasn't the name of the island itself.
* SuddenlyVoiced: ''Everyone''. The early games didn't even have ''subtitled lines''.
** Except Sonic and Eggman. [[http://www.youtube.com/watch?v=z0Qr0kSXGEg They talked]] in ''[=SegaSonic The Hedgehog=]''. (Ray and Mighty did too, but only Mighty reappeared, and even then only in ''[[VideoGame/KnucklesChaotix Knuckles' Chaotix]]''.) A few months later, Sonic sometimes exclaimed in ''VideoGame/SonicTheHedgehogCD'' (usually upon getting a OneUp).
* TacticalSuicideBoss: There are LOTS of them in this game.
** If Eggman never dug into the ground with the Egg Hornet, Sonic would have never destroyed it.
** Chaos 2 already has two very effective attacks: one has him bounce all over the arena as a giant ball, and the other covers the entire floor, so why does he have to try to punch Knuckles?
** Had Chaos 4 never popped out of the water, Sonic, Tails, and Knuckles would have never defeated him.
** When Sonic fights Chaos 6, Eggman throws ice robots onto the arena. All Sonic needs to do is attack the robot and throw it at Chaos to make him vulnerable. Chaos would have won had Eggman not gotten involved.
** Eggman should know better than to stick his head out of the Egg Viper.
*** He also should know better than to make its wheels separate from its body and move flat-side up.
* TeamRocketWins: Playing E-102 Gamma's story at least, which allows you to fight and defeat Sonic in battle (though Amy stops him just short of finishing the job). So far Gamma is the only one of Eggman's robots to individually defeat Sonic in the games storywise (albeit ''[[RashomonStyle branching]]'' storywise).
* TeethClenchedTeamwork: Knuckles' theme "Unknown from M.E." has a verse which he views teamwork, especially in regards to Sonic:
-->''I have no such things as weak spots'' \\
''Don't approve of him, but you got to trust him'' \\
''This alliance has a purpose'' \\
''This partnership is only temporary.''
* TempleOfDoom: Lost World.
* ThatsNoMoon: The excavation team at the Mystic Ruins is flummoxed by a "mountain" which suddenly appeared from nowhere. Unbeknownst to them (and the player, at first), it's actually Angel Island.
* TheVoiceless: Chaos never says a word, and Tikal is the one who relays his feelings to the audience.
* ThemeSongPowerUp:
** Played with in the final battle against Perfect Chaos. "Open Your Heart" (the game's main theme and Super Sonic's personal theme, more or less) plays during the first half of the battle. After you hit Chaos a number of times, it revives and the second half plays out under Perfect Chaos' own theme. It's subverted because Super Sonic doesn't defeat the creature for good while his own theme is playing, inverted because Perfect Chaos' own theme ("Perfect Chaos Revival!") is what plays during the second half (after it's rejuvenated) so Chaos is the one powering up to its own theme, and averted because it doesn't do a lick of good anyway (it's already losing by the time its music starts up; you just have to land the finishing blow (or two (give or take)).
** Again played with during the Sonic vs Gamma battle. Depending on who you play as, the character with the upper hand will have their theme play as they get ready to land the final blow. Amy will stop them just short of doing so however. In Sonic's case however, it continues so as to be played straight as he heads off to defeat Eggman and Chaos 6.
* TimedMission:
** Tails' stages have him racing against Sonic and, in the last level, Eggman. He has a limited amount of time to get to the goal before they do.
** All of Gamma's levels and his FinalBoss have a 3 minute timer. The timer can be increased by destroying enemies, with the amount granted being larger if more enemies are destroyed at once. The A-Rank versions of his stages shorten the timer.
** All of the A-Rank versions of the stages, with the exception of Big's levels, have a timer. Since Gamma's and Tails' levels are already timed in the other ranks, the time they are given is shortened.
* TranquilFury: In contrast to his usual LargeHam, Eggman's encounter with Tails in the Egg Walker has him speak this way. Surprisingly, it's very unsettling.
* TwoLinesNoWaiting: The game contains six subplots (seven if you count Tikal's) which all come together in the last story.
* UncommonTime: The boss music for Chaos 6 alternates between a 7/8 and a 4/4 time signature.
** [[http://www.youtube.com/watch?v=6WaLw12XZcY Fanfare 4 "Dr. EGGMAN"]] is in 7/4.
* {{Understatement}}: Gamma's concise nature of speaking creates such gems as "This is the wrong room" after accidentally walking in on his older brother being seemingly cannibalized for parts and upgraded while still active, or "This presents a problem" after being seemingly ''teleported back in time''.
* UnderwaterRuins: Lost World, in parts.
* UnderTheSea: There's watery segments here and there, but the only extended underwater segments are in Big's stages and are optional.
* UnusuallyUninterestingSight: Tikal and the other Echidna residents seem completely nonchalant about the heroes' presence, or even a ''friggin' robot'' in the flashbacks to the past. About the only reaction they will make is if the player attacks them or jumps on them.
* UnwinnableByInsanity: In the DX port, if you glitch your way into Twinkle Park with Knuckles and manage to get to the second part of the level, do ''not'' put Knuckles into the bowling ball launchers--it'll trap him in place and won't let you launch him, forcing you to restart or quit the level.
* UpdatedRerelease: The [=GameCube=] ''DX'' version, which added some more character cameos (namely Cream) and a catalog of Game Gear games. Further upgraded with the PSN and XBLA, with trophy/achievement support.
* UpgradeVsPrototypeFight: Gamma the robot is made to fight his "brother" Beta, who is the more advanced of the two. To Eggman's surprise, Gamma wins, so he is charged with carrying out the doctor's missions. [[spoiler:Later, Beta is rebuilt and battles Gamma again. Gamma just barely manages to win again, but unlike the previous battle [[PyrrhicVictory it results in his death]].]]
* UtopiaJustifiesTheMeans: [[spoiler:Pachacamac's reasoning for wanting the Chaos Emeralds taken from the shrine. It does nothing to cover up his power hungry nature and lack of regard for life at that point.]]
* VideoGame3DLeap: The true first one after the isometric ''VideoGame/Sonic3DFlickiesIsland''.
* VideoGameCaringPotential: Chao. If you are nice enough to a Chao, it will have a big smile on its face and clap whenever your character picks it up. Beware, however, that being ''too'' nice to a Chao might result in the little guy getting a spoiled personality, making it throw tantrums even when only a little hungry. Balance is the key, but regardless, if the Chao is happy enough, it will reincarnate into a baby at the end of its life.
* VideoGameCrueltyPotential: Likewise, you can hit the Chao, throw it, put it in water and watch it flail if it doesn't know how to swim, make it starve, and all other sorts of things. Such abuse will result in the Chao crying a fountain of tears, blowing a raspberry at you, or if it's aggressive enough, it'll charge at you and futilely throw punches. If the Chao is more sad/angry than happy, it ''won't'' reincarnate at the end of its life. You can kill your Chao outright this way.
** Also, in the original Dreamcast version, E-102 could actually ''shoot'' the Chao!
** To a lesser extent, as you play a stage as Sonic with Tails following you, you will find yourself attacking Tails. A few instances in doing this is by jumping in front of him or using a spin dash.
* VillainousBreakdown: A absolutely chilling one from Eggman at the end of Tails's story, not shown anywhere else. Due to the loss of both Chaos and the Egg Carrier, Eggman '''snaps''' and completely ditches his LargeHam and CardCarryingVillain tendencies and goes from a cackling, somewhat intimidating MadScientist to an OmnicidalManiac with a horrifyingly low growl of a voice. He then attempts to ''nuke Station Square'', and very nearly gets away with it if not for the missile being a dud. After Tails beats him to the missile and disarms it, Eggman snaps ''further'', jumps in a giant spider-mech and resolves to kill everyone himself. This line absolutely seals it:
--> '''Eggman''': (in a low growl, directed at Tails) You '''fool'''. Away! Before I make ''mincemeat out of you.''
* WhamEpisode: Besides being the series comeback into the mainstream, it shook a lot of things up in terms of content. The threat of Eggman is usurped by a monstrous, magical deity. The Chaos Emeralds are upgraded from bonus power-ups to magical, plot relevant artifacts with an elaborate backstory. The tone is darker and the stakes are raised much higher than previous threats in the series. This was also the first game in the franchise where a character (or rather, an entire civilization) was out-and-out killed.
* WhamLine: "Units remaining....[[spoiler: Gamma]]...Beta."
* WhatMeasureIsAMook: E-102 Gamma's story deconstructs this trope by virtue of being a playable {{mook}}. (Well, an EliteMook, but still).
* WheelOFeet: Sonic when running at top speed, but only in the original Japanese release of the game. The International version and all future versions removed the effect.
* WoobieDestroyerOfWorlds: [[spoiler:Chaos. He only acts antagonistically because he has been sealed away so long]].
* WordSaladLyrics: The themes of Knuckles and Big have their moments, but special mention goes to Amy's Theme:
--> I do understand the feelings of a Persian cat
-->(But the Sphinx looked so cute I had to shave it)
-->He reminds me of parsley when he's standing there all alone
-->(Makes me wanna be his speciality)
* YeahShot: All the characters' end of act poses. Sonic and Tails' endings do one as a CallBack to those of the classic Genesis games.
* YouHaveFailedMe:
** Eggman sorta does this to Gamma's E-Series brethren after they fail to retrieve the Chaos-enhanced Froggy, dispatching E105ζ (Zeta) for a torturous upgrade and demoting E103δ (Delta) and E104ε (Epsilon) to random areas.
** After Sonic, Big, and Knuckles foil their VillainTeamUp one last time and Eggman leaves him for dead on the sinking Egg Carrier, Chaos attacks the doctor out of spite before going solo. An angry Eggman later attempts revenge with the Egg Carrier 2, but Chaos, now in Perfect form, quickly swats him away again.
* YourCheatingHeart: A couple standing at the elevators at Station Square's hotel are arguing after the woman has discovered that her boyfriend is seeing another woman. Eventually, both women and the man are seen arguing at the swimming pool.
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