Sonic Adventure

"The fight is over, harmony is restored, and life goes on."

- Tikal


 * For other titles with "Adventures", see Adventures

Sonic Adventure (ソニックアドベンチャー) is a video game created by Sonic Team and released on 23 December 1998 in Japan by Sega for the Sega Dreamcast and is the first game in the Sonic Adventure series. One of its development titles was Sonic RPG (although the final product was an adventure game, and not a standard RPG). The final updated edition, known as Sonic Adventure International, was released on 9 September 1999 in North America, 14 October 1999 in Japan and Europe, 18 October 1999 in Belgium, the Netherlands, and Luxembourg, and 3 December 1999 in Australia. An enhanced port was released in 2003 as Sonic Adventure DX: Director's Cut for the Nintendo GameCube and in 2004 for the PC as 2x PC-CDROM discs. It has sold over 1 million copies in the United States alone, making it the top selling Dreamcast game. It is the first ever Sonic game on a sixth generation console. It received a sequel in 2001, marking the tenth anniversary of the Sonic the Hedgehog series.

Plot
A few millennia ago, the Chaos and Master Emeralds were kept at an altar near the territory of a clan of echidnas (the Knuckles Clan). A peaceful echidna named Tikal, daughter of Chief Pachacamac, befriended the Chao that lived at the altar and their protector, the water god Chaos. When Pachacamac sought to expand his clan's territory, he wanted to steal the Chaos Emeralds and use their power to defeat his rivals. Although Tikal and the Chao stood against him, he ordered his soldiers to charge anyway, resulting in many Chao being injured. This enraged Chaos, who transformed into a terrifying, giant monster and destroyed all of the echidnas, save for Tikal. Tikal sealed herself away in the Master Emerald with Chaos, and the magic caused the area surrounding the shrine to become Angel Island, also known as the continent in the sky.

In the present day, Doctor Eggman learns of the legend surrounding Chaos. Because he believed it to be true, he seeks out the Master Emerald and shatters it, freeing Chaos in the process. Eggman's goal is to control Chaos, and use its destructive powers to collect the Chaos Emeralds and conquer the city and turn it into "Robotnik Land." To help him, he has created the E-Series robots. When Sonic the Hedgehog learns of Eggman's plans, he and his friends spring in to action to stop Eggman and they start another journey for the Chaos Emeralds.

Sonic the Hedgehog's Story
In Station Square, Sonic witnesses a stand-off between a police force (possibly G.U.N.) and Chaos, a water monster. The police retreat, except for one officer, who stands there with his pistol. Sonic battles Chaos and he defeats it, but nothing could stop him escaping through a drain before Sonic gets answers.

The next day, Tails is testing a new plane, which he reveals to be powered by a Chaos Emerald, but he spins out of control and crashes. Sonic and Tails travel to the workshop, however, Eggman distracts them by showing up in the Egg Hornet. He was defeated but he could still steal the Chaos Emerald that they had, and reveals Chaos, the monster Sonic fought earlier. He explains that every time he gives Chaos one of the Chaos Emeralds, its power will be absorbed by Chaos.

Sonic and Tails counter Eggman's plans by getting all the Chaos Emeralds. They head to Windy Valley and Casinopolis, so they find two, but unfortunately, they drop them, and one of them is taken by Eggman, so they go to Icecap in the Mystic Ruins, to find another one. However, they run into Knuckles, who believes Sonic has retrieved some of the Master Emerald's shards. Then the two fight, and they drop BOTH emeralds. Eggman seizes his opportunity, and he takes the Chaos Emeralds and gives them to Chaos, who evolves into Chaos 4. They fight him in the pond, and after defeating him, Sonic and Tails chase after Eggman, but the Tornado loses its wing in the process. Sonic lands in Station Square, where he runs into Amy, who asks that he help her protect "Birdie".

However, Amy is kidnapped by ZERO, and Sonic chases. She is taken to the Egg Carrier, and Sonic chases on foot. Tails shows up with a remastered Tornado, powered by a Chaos Emerald. They give chase, land on the Egg Carrier and go through it in its transformed state, Sky Deck. They find Eggman, but he leaves once he has taken the Chaos Emerald from the bird. Amy prevents Sonic from destroying E-102. Sonic tells Tails to take Amy to safety while he chases Eggman.

He finds Eggman, who has given Chaos two more emeralds for a total of six. Chaos 6 appears right in front of them, and Sonic almost defeats Chaos when Eggman leaves. Sonic leaves Chaos at Knuckles' mercy, and follows Eggman. However, he mistimes his jump and lands in the jungles of the ruins. While exploring some of them, (Lost World), he's taken back in time, to a point in time when Tikal and the shrine are under attack. Before he can learn anything, he is returned to the present. He follows Eggman into his main base, Final Egg, and they have one last fight. After defeating him, Sonic and Tails take another break. Sonic saved the day once again.

Miles "Tails" Prower's Story
Miles "Tails" Prower flies in a new plane until it suddenly crashes by the beach in Station Square. After Sonic rescues him, Tails reveals that the plane was powered by a Chaos Emerald and the two plan to meet in the workshop in the Mystic Ruins to design a new plane with that Chaos Emerald. Here, they are met by Eggman in the Egg Hornet. After it is destroyed, Eggman steals the Chaos Emerald and feeds it to Chaos, who just arrives.

Tails and Sonic head to the Windy Valley and Casinopolis to collect two more Emeralds; however, one of them is taken by Eggman. They head to the Mystic Ruins to collect another Emerald. Upon leaving Icecap, they encounter Knuckles. Due to a misunderstanding, Tails and Knuckles fight. Eggman, taking advantage of the situation, snatches away the Emeralds, giving them to Chaos. After a battle with Chaos 4, Eggman escapes in his Egg Carrier. Tails and Sonic give chase in the Tornado, but the Tornado gets shot down in the process. Tails lands in Mystic Ruins, only to find out that Sonic is missing and the train workers are on strike (cutting off access to Station Square). After a flashback about the "good old days", Tails decides to do without Sonic and ventures into the jungle in search for a Chaos Emerald to rebuild the Tornado. He finds a red emerald here, but runs into Big's friend, Froggy (with Chaos' tail), which swallows it. After giving chase through the Sand Hill, Tails catches up with Froggy, but is taken back in time and meets Tikal. When returned to the present, Big accidentally gives Tails a shock, causing him to lose grip of Froggy as a result.

Next, the Tornado 2 is built. During the flight, Tails meets up with Sonic at the peak of Red Mountain and gives chase to the Egg Carrier. Despite stormy weather, the two managed to evade much of the Egg Carrier's attacks. Upon landing, Eggman immediately activates the transformed state that deactivates the monorails. Then, Sonic and Tails go through the Sky Deck. They find Eggman, Amy and E-102. Sonic tells Tails to take Amy to safety while he goes after Eggman. Next, the Egg Carrier collapses, and Tails and Amy make it safely to Station Square. Amy bids goodbye to Tails, soon after Eggman (having been defeated by Sonic) crashes nearby the train station. Undaunted, Eggman launches a missile as a last ditch attempt but it turns out to be a dud. Angered, Eggman blasts the doors of a skyscraper and threatens to detonate the missile. Tails, realizing that the fate of the city is in his hands, gives chase. After a long endurance race through the night, Tails reaches the missile first and deactivates it. Frustrated at his failure, Eggman unleashes an Egg Mobile - the Egg Walker, and prepares to annihilate Station Square. All of the citizens run for shelter, leaving Tails - without Sonic's help, to fight with Eggman. In the end, Tails wins and the citizens cheer. While heading back to the workshop in Mystic Ruins, Tails meets up with Sonic to end the story.

Knuckles the Echidna's Story
As Knuckles the Echidna rests beside the Master Emerald thinking over the story of his life, he wakes up to find Chaos next to the shattered Master Emerald. Unaware that this is Eggman's doing, Knuckles assumes that Chaos is behind the shattering of the Emerald and goes on to attack it. However, the beast blindsides him and escapes, and suddenly Angel Island falls into the sea next to the Mystic Ruins. Knuckles arrives in Station Square to find the pieces of the Master Emerald. He finds a few pieces in Speed Highway and Casinopolis, but is flashed into the past to a place he's never seen before (but is somehow familiar to him.) He overhears Tikal trying to stop her father, Pachacamac, from invading someone's "sacred grounds," but returns to the present before getting the details. He then spots Eggman heading into an elevator in the hotel. He notices the shine in Eggman's hand and believes it to be a piece of the Master Emerald so he follows Eggman. Knuckles then gets into a fight with Chaos 2, and after winning the battle, Eggman tells Knuckles that Sonic is after the emerald pieces. This gets to Knuckles, wondering why the blue blur would want them. He then heads into the jungle (where a power-up is found). Knuckles heads to Red Mountain and finds three more shards. A few minutes later, Knuckles finds Sonic and the two duke it out. But it was all a trick from Eggman so he could nab the two emeralds they had. He gives them to Chaos, causing him to transform into Chaos 4. Knuckles does eventually defeat him; Sonic and Tails go after Eggman, and Knuckles goes solo to find the rest of the pieces.

A moment later, Knuckles finds the keys to an abandoned Ziggurat called "The Lost World", and finds three more shards, and is sent back to the past. He meets Tikal again, and is sent to his time... right in front of the altar. 85% of the Master Emerald is restored. The last three shards are on Eggman's fortification, the Egg Carrier, but Knuckles has no idea where the fortress is. As he walks across the bridge, he spots Gamma heading to the jungle. He decides to follow the rogue to the jungle and into the fortress, which takes off. Soon, he eventually finds the last shards, but ends up getting sent to the past, this time with the altar under a thick flame. He walks over to Tikal and attempts to find out what's going on, but fails when Tikal rushes to the Emerald, causing him to get sent to his time. He spots Eggman and Chaos and rushes towards them. Eggman retreats, with Sonic on his heels. This leaves Chaos, who has devoured 6 of the Chaos Emeralds, at Knuckles' merciless spines. After a long battle, Chaos relinquishes the Chaos Emeralds and retreats, with Knuckles saying "Yeah, you're finished!!" The Egg Carrier loses its balance and self-destructs, but Knuckles flies back to Angel Island to prevent himself from getting burned.

Back at the Island, Knuckles restores the Master Emerald to its normal state, allowing the giant gem to hoist Angel Island to the heavens. Knuckles is once again at peace. The Master Emerald is repaired for the first time.

Amy's Story
Amy Rose is taking a stroll in Station Square, reminiscing about the good old days when suddenly the city is shadowed by the Egg Carrier and a bird falls down from the sky. The bird was held captive, along with its family. Amy befriends the bird,who she nicknames "Birdie", and promises she'll help it get home with its family. After a stroll through the town, she runs into Sonic and asks him to guard the bird, though Sonic strongly declines. She follows him to the entrance of Twinkle Park. Unfortunately, ZERO appears and before Sonic can do battle with it, Amy notices a sign that apparently says "Cute Couples get in free" and readily enters the park while Sonic follows trying to stop her. After making her way through Twinkle Park while avoiding ZERO, she makes it back to Station Square and finds Sonic gone. Before she can continue with her search, she is captured by ZERO.

Amy is taken to a cell aboard the Egg Carrier where she is guarded by E-102 Gamma. He demands she hand him the bird, but she refuses. She then demands that he tell her why he wants the bird, but he himself does not know. She pleads with Gamma to help them, but he questions why she cares for something she knows nothing about. She says she pities him because love is not a part of his programming. The bird flies out of the jail cell and looks Gamma in the eyes. Gamma then tells them to escape and deactivates the cell. He tells them it is dangerous and that they'll be at the Mystic Ruins base soon. She comes to a room and plays through a game where she gets the Warrior's Feather. While venturing through Hot Shelter, she has another run-in with ZERO. When she grabs a hold of the balloon, she drifts back in time and meets Tikal after finding Chaos' Shrine. She then drifts back into the Egg Carrier. She makes it to the deck and is cornered by Eggman. Fortunately, Sonic and Tails also make it to the deck. Eggman grabs the bird and take the Chaos Emerald around its neck. He calls out Gamma who is ordered to destroy them. After fighting Gamma, Sonic tries to deliver the final blow, but Amy defends the robot, telling Sonic he helped her. The Egg Carrier begins to lose altitude and Amy tells Gamma to be free. Gamma asks why she is helping him, to which she responds that she promised they'd be friends. She then leaves with Tails as the Egg Carrier crashes.

She returns to Station Square and bids farewell to Tails and goes to Mystic Ruins to help the bird find its family. After searching through the jungle she finds the bridge leading to Eggman's base. She goes through Final Egg and once again meets with ZERO, but escapes. After deducing that the bird escaped from the Egg Carrier, she goes back to the now sunken Egg Carrier. The bird finds its family but ZERO knocks out the bird with its telescopic fist. After noticing the perpetrator of the attack, Amy becomes enraged and prepares to fight Zero. After battling and eventually destroying the robotic pursuer, the three birds are reunited and Amy vows to be the best she can be to impress Sonic, and hopefully make him respect her.

Big the Cat's Story
Big the Cat is sleeping on his bed when Froggy, his best friend, awakens and spots Chaos. Froggy bites off Chaos' tail causing him to grow his own tail. Big wakes up and is worried about Froggy, who is driven insane by the possession. Froggy devours a Chaos Emerald (which Big calls his lucky charm) and runs away, with a worried Big following.

When the sun rises, Big finds himself in Station Square, where he sees the crazed Froggy go in the sewers. He hoists a black car, and follows Froggy to Twinkle Park. Big manages to fish Froggy out, but the crazed amphibian retreats. Big soon finds a key to Icecap, grabs a Life Belt and heads into the icy area. He fished Froggy out, but Froggy, due to insanity, takes off.

Big heads towards the Emerald Coast and finds Froggy on one part of the Great Sea. After fishing him out, Big turns to go home, but Gamma grabs the crazed frog from Big and heads back, with the worried feline pleading behind. Big boards the Egg Carrier, and tries to pick up Froggy's scent, but fails, so he decides to find him in the Hot Shelter. He realizes that to get Froggy out, He must activate the switch. After doing this and fishing Froggy out for the last time, Big turns to exit, but is transported to the past. He encounters Tikal for the first time and returns to his normal time. He gets out of the Attendance room and heads out, but spots Chaos and freezes in horror at the sight of him. Eggman arrives and gives Chaos the emeralds, causing him to enlarge again. Froggy then hops into Chaos's body, restoring the beast's tail. Sonic arrives and realizes Chaos's gotten bigger. Big carefully fishes Froggy out of Chaos's body and escapes under Sonic's orders. Suddenly, the Egg Carrier is about to lose altitude, but Big spots the Tornado 2 and flies to the jungle moments after the flying fortress self-destructs and crashes into the Great Sea.

Big and Froggy are now home and enjoying peace again. Froggy is no longer insane, and Big is celebrating.

E-102 Gamma's Story
Dr. Eggman introduces himself to the second robot in the E-100 series, E-102 Gamma, who awakens. His training involves Gamma seeking and searing the Sonic doll in Final Egg. After that, Eggman introduces Gamma to his older brother, E-101 Beta, and pits them to a small duel. Gamma achieves victory, but Beta boards the Egg Carrier for repairs and an upgrade. The fortress flies off into the skies.

A moment later, Eggman announces to Gamma and his younger brothers, E-103 Delta, E-104 Epsilon and E-105 Zeta, to find and capture Froggy, who's been driven insane by Chaos' tail and has eaten a Chaos Emerald. Gamma heads to the Emerald Coast, grabs Froggy and is about to return when a blinding flash takes him back in time. He tries to figure his location, but it doesn't work. He heads to the alter and lowers his cannon at the presence of the Chao. Tikal rushes to their aid, but she realizes Gamma's not part of the Knuckles clan and gives him some helpful information about the Chaos Emeralds, the Chao and their draconian protector, Chaos, before Gamma reverts to his time.

After that, Gamma and his brothers argue over whose frog is the one, but stop when Eggman walks in. Irritated, Eggman tells them that the frog he wants is crazed, has Chaos's tail and even ate a chaos emerald... but settles when he spots Froggy in Gamma's hands. He proudly congratulates Gamma for his capture and dismisses Delta, Epsilon and Zeta for their idiotic failure. He then tells Gamma to find the bird with Amy, then departs. Gamma accidentally gets into the wrong room, where he spots Beta being repaired and upgraded. He quickly gets to the dungeon where he encounters Amy and the bird (named Lily in Sonic X), and attempts to persuade her to give him the bird. Amy persistently ignores his orders and tells him that love isn't part of his programing, which Gamma angrily replies that she knows something that she shouldn't know. Then the bird flies to Gamma and looks him straight in his eyes. Agitated, Gamma orders them to flee by opening her cell, then heads to the attendance room, where Eggman orders him to get the jet booster from the ammunition room. After that, Gamma heads to the main bridge of the Egg Carrier and engages Sonic in battle. Just as he is about to sear Sonic to ash, Amy interferes. She tells him to remember her and says that he should ditch Eggman, much to Sonic's surprise. Suddenly, the Egg Carrier is about to lose altitude. Sonic races off after Eggman, while Amy says that she and Gamma be friends. He asks why she's helping him, and she replies that friends always help one another. Gamma, Tails and Amy escape as the Egg Carrier self-destructs and crashes into the Great Sea.

Searching his files, Gamma realizes Amy's words and decides to go 'rogue', beginning his own quest to find and save his brothers. He finds a switch to Windy Valley, explores it completely, spots Delta and battles him. Following this, He heads to Red Mountain, goes in the magma chamber of one volcano, finds Epsilon and defeats him. After that, he realizes Zeta and Beta are on the Egg Carrier and heads towards it via canoe. Gamma enters the Attendance Room and opens the doors to the Hot Shelter lair, where he goes through its tunnels and spots Zeta, who has transformed into a large cylinder-like monster. Gamma engages in battle, sears Zeta's head off and gets out of the Hot Shelter. He gets out of the Attendance room and spots Beta flying towards a field. He heads to it and engages him in battle.

After a long battle, Beta crashes to the ground. Gamma walks over, but Beta shoots him at point-blank range in the face, sending him back. Beta self-destructs and releases a bird, just 20 seconds before Gamma does the same. This brings a tragic end to Gamma, but he has set all the animals free and accomplished his duty.

Final
It is revealed that Chaos has survived. Eggman mutters about his hatred of Sonic, knowing that he cannot spoil his master plan. He stops and spots Chaos, who mauls him. Angel Island has fallen again.

Knuckles knows this as well. He decides to take the Chaos Emeralds to Sonic as advice, but spots Eggman lying on the ground. Eggman's mutter of pain is "This is terrible!! C-Chaos is..." Knuckles asks "Is what?", but is interrupted when Chaos appears and attacks them both, stealing the Chaos Emeralds.

Sonic is relaxing by a tree when Tails tells him that Angel Island has fallen. When they get there, they spot Knuckles and Eggman in serious pain and are exhausted. Knuckles tells Sonic and Tails that Chaos has survived and has stolen his Chaos Emeralds. Eggman heads off on his mobile and searches the jungle for a replacement fortress. Knuckles tells Sonic about Chaos' ferocity and states that if he gets the last Chaos Emerald, death will come. Sonic knows that he'll find it before the renegade does, but is sent to the past for the last time. This time he spots the Altar under attack from the Knuckles clan, who knocks Tikal to the ground and injures many Chao. This enrages Chaos, who devours the Chaos Emeralds and goes berserk. Sonic heads over to Tikal and asks if she's okay. Tikal realizes Chaos is wreaking havoc and seals him and herself within the Master Emerald for all eternity, in order to stop him before it is too late.

Sonic returns to the present day. Tails says that they have to get the last emerald before Chaos does. They head over to Big's hut and spot the Tornado 2. They are about to get the emerald, but Chaos devours it and goes on a rampage in Station Square, flooding the city. Sonic, who now realizes how vicious Chaos really is, spots the Egg Carrier 2 from the corner of his left eye and knows that Eggman is after the renegade. Eggman attempts to engage in combat, but Chaos demolishes the fortress to ruin with a massive beam of energy. Sonic is getting aggravated with Chaos's ferocity, but Tikal arrives. Sonic realizes Tikal sealed Chaos in the Master Emerald. She states that her heart's been always with the Master Emerald as well as Chaos', but he's full of rage and tragedy. If this he isn't stopped, he will bring destruction to the Earth like he did centuries ago. Chaos then discards the now powerless Chaos Emeralds; and Tikal demands that Chaos be resealed in the Master Emerald, but Sonic refuses, telling her that doing so won't change how Chaos feels from within. His heart will still remain in turmoil and his anger won't vanish; he'll just be trapped forever, and history will just repeat itself as it did before. Instead, Sonic opts for another solution: destroying the anger and rage within Chaos' heart. Sonic's allies gather the Chaos Emeralds and Tails states to Sonic that Chaos has absorbed the Emeralds' negative power, and that Sonic should be able to harness their positive power. Closing his eyes and using the positive energy of his friends and the citizens of Station Square, Sonic restores the Chaos Emeralds to their normal state and transforms into Super Sonic. He then flies off to engage the gargantuan god/beast in battle.

Two phases later, Chaos is reverted to his normal form, Chaos 0,  his anger and rage faded. He spots several of his organic kin, the Chao, and knows of their peacefulness. Tikal arrives and tells Chaos that the Chao have been living peacefully with mankind for a long time and continue to do so. With the fighting over and harmony restored, the circle of life moves on. She and Chaos then return to their time. Seconds after, Eggman flies away. Peace is back once more, and Sonic runs off to catch Eggman before he's in search of more adventures.

Levels

 * Emerald Coast - Sonic, Big and E-102 Gamma (Tails, Knuckles, and Amy via glitch)
 * Windy Valley - Sonic, Tails and E-102 Gamma
 * Casinopolis - Sonic, Tails and Knuckles (E-102 Gamma via glitch)
 * Icecap - Sonic, Tails and Big
 * Sky Chase Act 1 - Sonic and Tails
 * Twinkle Park - Sonic, Amy and Big (Tails, Knuckles, and E-102 Gamma via glitch)
 * Speed Highway - Sonic, Tails and Knuckles
 * Red Mountain - Sonic, Knuckles and E-102 Gamma
 * Sky Chase Act 2 - Sonic and Tails
 * Sky Deck - Sonic, Tails and Knuckles
 * Lost World - Sonic and Knuckles
 * Final Egg - Sonic, Amy and E-102 Gamma
 * Hot Shelter - Amy, Big and E-102 Gamma
 * Sand Hill - Tails (Side Mission), Sonic (optional)

Bosses

 * Chaos 0 - Sonic
 * Chaos 2 - Knuckles
 * Chaos 4 - Sonic, Tails, and Knuckles
 * Chaos 6 - Sonic, Knuckles, and Big
 * Perfect Chaos - Super Sonic
 * Egg Hornet - Sonic and Tails
 * Egg Viper - Sonic
 * Egg Walker - Tails
 * Zero - Amy
 * E-101 Beta - E-102 Gamma
 * E-102 Gamma - Sonic and Tails
 * E-103 Delta - E-102 Gamma
 * E-104 Epsilon - E-102 Gamma
 * E-105 Zeta - E-102 Gamma
 * E-101 mk2 - E-102 Gamma

Mini-bosses

 * Sonic - Knuckles and E-102 Gamma
 * Knuckles - Sonic and Tails
 * E-102 Gamma - Sonic and Tails

Characters
Unlike the previous action game in the series, Sonic 3D Blast, Sonic Adventure has six different characters to choose from, providing two more than the four (Sonic and Tails combo being the fourth) available in the earlier Sonic 3 &amp; Knuckles.

Sonic the Hedgehog
The main hero of the game with supersonic speed. Sonic's story revolves around Dr. Eggman releasing Chaos from the Master Emerald. Sonic battles Eggman and Chaos in an effort to save Earth, as well as finding the Chaos Emeralds before they do. Sonic has the most stages of any character (the only stage Sonic does not go to is Hot Shelter), and his levels involve high speed gameplay.

Miles "Tails" Prower
After Sonic rescues Tails from Emerald Coast after a "Tornado" prototype experiment goes wrong (and crashes), the latter sets out to help Sonic collect the Chaos Emeralds and stop Chaos. Most of his levels are abridged versions of Sonic's, which require him to reach the end of the level before Sonic (or Eggman in the last action stage) can.

Knuckles the Echidna
Knuckles is the guardian of the Master Emerald and one of the main protagonists after Sonic and Tails. The Master Emerald shatters when Eggman frees Chaos and Tikal's spirit from within it, causing Angel Island to fall out of the sky. Knuckles' goal is to reassemble the shards of the Master Emerald. His stages are enclosed areas where Knuckles must find shards of the Master Emerald. He can glide through the air and scale most walls.

Amy Rose
Amy Rose is walking through Station Square one day when a tiny blue Flicky falls from the sky and lands on her head. It is discovered that Dr. Eggman needed this Flicky (nicknamed "Birdie" by Amy) because of the Chaos Emerald in its pendant. Amy and Birdie must escape ZERO (otherwise known as ALPHA), one of Eggman's robots. Her primary weapon, the Piko Piko Hammer, returns, as it was previously seen in Sonic the Fighters. Amy is considered to have the shortest story since she has fewer levels than the other characters, despite their length being second only to Sonic's. Amy's levels involve a few puzzles, while going though lanes and paths. Usually ZERO comes in the most surprising ways, to try and capture Amy. The usual goal is to find the yellow balloons at the end of the levels.

Big the Cat
Big the Cat is a newcomer to the Sonic series. Big's best friend is a frog named Froggy, who became possessed by Chaos' tail, and swallows Big's "lucky charm", a Chaos Emerald, which causes him to mutate. The frog then runs off, and Big's story begins.

His levels involve using his fishing pole to try and catch Froggy, although he can also choose to try and catch big fish, with score bonuses based on size.

E-102 Gamma
E-102 Gamma is one among a series of Eggman robots designed to take orders without question. After an encounter with Amy, he suffers a malfunction and gains a "conscience". He then turns his aim to destroying his robotic brothers and freeing the animals trapped inside them. "Gamma" is one of the letters in the Greek alphabet. Gamma's levels are shooting levels in which the player races against the clock to get to the end and destroy the target (usually one of the other E-Series robots). Players gain time depending on how many enemies they shoot in a row/chain by using the lock on feature that Gamma has.

Super Sonic
Super Sonic is unlocked after the stories of the other characters have been completed. The story is a continuation of Sonic's story and brings all of the characters together to face Perfect Chaos. When in his Super State, Sonic moves faster and attacks by gaining speed and ramming into Perfect Chaos. Super Sonic was originally going to be playable in the Action Stages (implied by an unused voice clip explaining how to turn into Super Sonic) but was scrapped, most likely due to time constraints.

Metal Sonic
Metal Sonic is unlocked after getting all the emblems. He is only an alternate costume for Sonic and has no story of his own. He replaces Sonic's story. This feature is only available for Sonic Adventure DX and not in the original Sonic Adventure. He also has different sound effects.

Dr. Eggman
Dr. Ivo Robotnik, also known as Dr. Eggman because of his round body shape, has formulated a new plan to conquer the planet, this time not relying on his robots alone, but befriends a strange liquid creature known only as Chaos (who ends up betraying him).

Note: This is the first console game to significantly adopt "Eggman" in the West.

Chaos
Chaos is the guardian of the Chao, and is actually a mutated Chao himself. He is apparently made of water or a plasma-like material and continually changes form after consuming a Chaos Emerald. After consuming all seven Chaos Emeralds, it turns into Perfect Chaos and starts destroying the city, until Super Sonic defeats it (in actuality, he neutralizes the hatred within Chaos's heart, which was causing it to function within a state of blind rage).

Tikal
A mysterious female echidna who appears whenever Sonic, Tails, Knuckles, Amy, E-102 Gamma, and Big are sent back in time. She is trying to stop her father, Pachacamac, from stealing the Chaos Emeralds from the Master Emerald shrine. She appears mostly in the form of a pink ball of light called a Hint Orb.

Zero
Zero is one of Eggman's robots sent to find Amy's friend Birdie. He follows Amy wherever she goes hoping to capture her and the bird. At one point, he succeeds, but Amy is rescued by E-102 Gamma. Eventually, Zero is defeated by Amy Rose on the Egg Carrier. Zero is the antagonist of Amy's story due to him trying to catch the bird.

Chao
Chao are featured in the flashbacks, said to be Chaos' children. They exist primarily in the Chao Gardens as a sort of intelligent virtual pet for the player to raise, an "evolution" of the A-life system from NiGHTS into Dreams... Chao can be taken with the player by downloading the minigame Chao Adventure to his/her VMU, or in the GameCube version, by downloading the Chao to a Game Boy Advance.

E-100 series
Dr. Eggman's E-100 Series series of robots play a large role in Gamma's story, as he is one of them, and is out to destroy or "save" the others. All of them have letters of the Greek alphabet as part of their name.
 * E-100 "Zero" (Description above). Note that E-101 Beta is the first in the E-100 series in this game. The anime, Sonic X, later established Zero's model number as "E-100" (thus moving E-101 to second in the series, mildly contradicting Sonic Adventure). Note, all the E-100 Series are named after letters in the Greek Alphabet, Therefore due to being described E-100, he is given the name Alpha as well as Zero, due to Beta being the second letter in Greek Alphabet, making Zero/Alpha a letter before him due to being E-100.
 * E-101 Beta is a black robot with two gun arms. He is the first boss in E-102 Gamma's side of the story, and is later upgraded into E-101 Beta Mk II, who is Gamma's fifth and final boss. Beta is the antagonist of Gamma's story.
 * E-103 Delta is a blue robot who is Gamma's second boss, waiting at the end of Windy Valley.
 * E-104 Epsilon is an orange robot who is the third boss of Gamma's side of the story and is fought at the end of Red Mountain.
 * E-105 Zeta is a purple robot who is Gamma's fourth boss and is located at the end of Hot Shelter. While at first humanoid, Zeta is altered into a cylinder-like form with several turrets.

NiGHTS
NiGHTS makes a cameo in the Casinopolis stage where there is a pinball stage based on the NiGHTS series. In fact, the music that plays is taken directly from NiGHTS Into Dreams...

Cream the Rabbit
Cream makes a few appearances in the game but only as cameos and doesn't speak or even interacts with the player. Cream only appears in the Sonic Adventure DX: Director's Cut and the PC, Playstation 3 and Xbox 360 re-releases.

Development
According to an interview with Takashi Izuka, the Sonic World environment featured in Sonic Jam was a prototype level for Sonic Adventure and that the game was at one point going to be made for the Sega Saturn, but said that "due to technical issues and the timing of the upcoming Dreamcast project, we had to end it and instead incorporated it into the Saturn's Sonic Jam. We then moved development for Sonic Adventure on to the Dreamcast." A Japanese commercial of Tails for the release of Sonic Adventure showed some gameplay footage of Sky Chase Act 2 with what appears to be Sonic and Tails in their 3D models from Sonic 3D Blast (Sega Saturn version), Sonic Jam and Sonic R, which hints at the fact that the game may have been intended for the Saturn (the footage is actually from the Dreamcast, with the Saturn models as stand-ins while the newer models were being completed).

With the release of Sonic Generations, it was explained in another interview that the updated look of Perfect Chaos in that game was how it was originally designed for Sonic Adventure, but couldn't be done due to technological restraints on the Dreamcast. Instead, Perfect Chaos' body in Sonic Adventure was done to look like it was made completely out of water, which was still something beyond what the Saturn would have been capable of.

Story Structure
The story is told through the perspective of the character you choose to play as and as a result the stories tend to diverge at certain points based on the character arc. It is interesting to note that the story takes on a certain Rashomon type structure in terms of dialogue and certain events when more than one of the playable characters is present in a scene. For example, each character has their viewpoint of a certain scene, so the dialogue between versions tends to be different. This perspective also justifies the different outcomes of certain encounters, for example, when Sonic faces E-102 Gamma on the Egg Carrier, through Sonic's perspective Sonic is about to destroy Gamma, through Tails' perspective Tails is about to destroy Gamma and through Gamma's perspective, Gamma is about to kill Sonic.

Gameplay
The game is divided up into two stages: Action Stages, and Adventure Fields. The division of Action Stages and Adventure Fields was a serious departure from all previous Sonic games.

Action Stages
Action Stages are basically playable levels. This is the only type of area where Sonic or any of his companions will encounter enemies (most boss battles appear to take place in the Adventure Fields, but they are actually in Action Stages designed to look like the Fields). There are eleven Action Stages, accessible by different characters. However, unlike previous Sonic games, Action Stages are not made up of Zones and Acts. Instead, the game plays more like each Adventure Field is a Zone and the Action Stages are the Acts in the Zone. The Action Stages have separate areas that could be considered "Acts", but they are not separate levels, as in previous games.


 * Emerald Coast
 * Windy Valley
 * Casinopolis
 * Icecap
 * Twinkle Park
 * Speed Highway
 * Red Mountain
 * Sky Deck
 * Lost World
 * Final Egg
 * Hot Shelter

Sub Games
Sub Games are mini games based on action stages. When you complete a sub game on Story Mode, you unlock it on the sub game menu located on Trial Mode. For some Sub Games you can use any character, but some of them require the use of the character(s) from Story Mode. You can get two emblems from each sub game, from achieving high scores. The second emblem requires a much higher score than the first. The scores appear at the end of a sub game. You cannot get two emblems per character but can use any to get one emblem (if it allows more than one character).

Adventure Fields
Adventure Fields are non-linear game stages, generally designed for (light) puzzle solving, exploration, and plot advancement. They contain very few items (enemies, rings, etc.). Every Adventure Field links to the other two Fields and a Chao Garden. They also have four Emblems each. They are each packed with various power-ups for different characters.

There are three Adventure Fields:
 * Station Square: a large, metropolitan city, and is the location of Sonic's first fight with Chaos. Eggman plans to destroy it and construct "Robotnikland" on its ruins. A train here takes you to the Mystic Ruins.
 * Mystic Ruins: a large mountainous area and the largest Adventure Field in the game, containing the crashed Angel Island. A train here takes you to Station Square. Deep in the jungle, a Ziggurat can be found. Tails' workshop is in this area. It also has a base home to Eggman.
 * Egg Carrier: Eggman's massive flying airship. This is the Adventure Field where most characters fight their final bosses (except Sonic and Tails). The Egg Carrier has two layouts and multiple transport devices unique to this field.
 * Egg Carrier Crashsite: This area appears when the Egg Carrier crashes. This is an early stage for E-102 Gamma. There are two boats, one leads to Station Square while the other goes to the Mystic Ruins.

Basic move commands (XBLA)
Left Stick or D-pad-Move character A button-Jump X or B Button-Action LT, RT, LB or RB-Rotate camera Right-stick-Change camera view

Character specific commands
Sonic:
 * Spin Dash - Hold the Action button while standing still and release it.
 * Homing Attack - Press the Jump button and while in mid-air press the Jump button again.
 * Light Speed Dash/Attack (Requires Light Speed Shoes/Ancient Light - Hold the Action button while standing still for Sonic to begin charging. Once Sonic stops charging, approach a trail of rings/enemies and release the Action button.

Tails:
 * Flying - While in mid-air, press and hold the Jump button to ascend for a short time before Tails gets tired and drops down. While flying the player can press and hold the Action button to come back down to the ground quickly.
 * Tail Swipe - Press the Action button to attack enemies in front of Tails.
 * Rapid Tails Attack (Requires Rhythm Badge) - Press and hold the Action button. This can be done continuously as long the player holds the Action button.

Knuckles:
 * Glide - While in mid-air press and hold the Jump button to glide across the air. If the player release the Jump button, Knuckles will stop gliding.
 * Climb - By gliding to a wall, Knuckles will stick to the wall. The left stick is used to scale around the wall in any direction.
 * Punch Attack - Press the Action button three times for a dash punch attack.
 * Dig - Press both the Jump and Action buttons simultaneously to dig up buried items.

Amy:
 * Hammer Attack - Tap the Action button to attack with the Piko Piko Hammer.
 * Hammer Jump - While running press the Action button to jump higher than normal.
 * Jump Attack - Press the Action button while in mid-air to attack enemies in the air.
 * Revolving Hammer Attack (Requires the Warrior Feather) - While standing still, hold the Action button while spinning the left stick around.

Big:
 * Casting - Press and hold the Action button to display the cursor and position the target location with the left stick. If successful, Fishing mode commences. This can also be used to attack enemies from far distances.
 * Lure Attack - Press the Action button for a melee range attack.
 * Dive - Press and hold the Jump button to dive and release to resurface.
 * Fishing Mode - Once a fish or Froggy bites onto Big's fishing rod, use the left stick to tug the rod, Jump button to reel in quickly or either Action button to reel in slowly.

Gamma:
 * Lock-on laser - Hold the Action button and move the left stick to quickly pin-point enemy targets. Release the Action button to destroy the enemy targets.
 * Hover - While in mid-air, press the Jump button to slowly descend while moving around.

Reception
The reception at the time of release was overwhelmingly positive, including reviews from GameSpot and GameSpy being above 90%. It is considered one of the best games in the series. The current Game Rankings average ranking is 88%. It became one of the few Sega All Stars games. In Japan, it received a nearly excellent score of 38/40 from Famitsu. Similar to its sequel, however, the later-released GameCube port was criticized by many of the same sources who praised the Dreamcast version, although in this case, the Directors Cut reportedly didn't play as well as the original version did. Sonic Adventure DX: Director's Cut averaged a 63% at Game Rankings, as well as being rated one of the top five Sonic games by ScrewAttack.

Sonic Adventure: Limited Edition


Sonic Adventure: Limited Edition is a special pre-release of the North American edition of Sonic Adventure for the Sega Dreamcast, and was made to show the connection between Sega and the Hollywood studios. In July of 1999, the game was made available for rent for a limited time and until two months its features would vanish. In 2008, retail and pre-production images of the Sonic Adventure Limited Edition GD-ROM were dumped by drx.

Sonic Adventure International
Sonic Adventure International is a revision of the original Sonic Adventure. It is essentially the version of Sonic Adventure that was distributed worldwide, with minor polishing touches. This re-release was deemed necessary due to Sonic Adventure being rushed to the Japanese market and having several programming errors and unimplemented features. The North American release had approximately ten months of development time. It is the final edition released for Dreamcast, and contains several of the changes made for worldwide versions including:


 * There are more options available, such as a complete English voice track added alongside the Japanese one. The in-game text can be selected in five different languages: English, Japanese, French, Spanish, and German. Other languages tend to follow the English script rather than the Japanese one (for example, references to Dr. Robotnik). The English settings are default in all regions. In addition, there is optional rumble support.
 * Some cutscenes contain slightly different sound mixing, as well as angle and timing differences. One noticeable instance is the cutscene after Sky Chase Act 1 in Sonic's story, which has a camera angle closer to the girl's perspective in the re-release rather than Sonic. Another example is the short cutscene when Knuckles first arrives in the Mystic Ruin, in which it originally played Tikal's theme rather than the Mystic Ruins area. Yet another difference is when Gamma lands in the Mystic Ruin, in which he was not shown actually landing. During Tikal's final flashback, Chaos also originally emitted a wounded Chao noise rather than a roar from his later forms when he uses the Master Emerald. Note that individual character animations are also slightly different in terms of speaking and action.
 * Some visuals were altered for unknown reasons, which is evident right on the updated title screen which includes water ripples (although earlier North American copies have the original title screen). For instance, Sonic's running animation in top speed originally had a unique blurring "wheel" effect akin to the classic games, and his victory animation did not have him giving a thumbs up. Another example is a stylized cowgirl billboard that waved a 3D martini glass and made suggestive noises when attacked, which was replaced by an inconspicuous Casinopolis decoration. The models for the Flickies were also adjusted in International, as their wings originally had an odd wing joint. Chaos' puddle in the Super Sonic story also originally included his tail, but it was removed since it looked glitchy.
 * Some sound clips are missing altogether in the initial release, such as characters cheering from the boosters in Twinkle Circuit, idle animations having unique lines of dialogue for each location, virtually all of Gamma's gameplay voice clips (making him silent outside of cutscenes and his rival battle), and certain other clips like the announcements at the train stations. Other sound effects were changed entirely, such as the lasers of the Egg Viper.
 * The pinball boards in Casinopolis can now be shaken to adjust Sonic's trajectory, and there is a new ball counter.
 * Some of the menus were better organized such as those under "Trial", which now include Emblem Results.
 * Even though it was already in English, the Hedgehog Hammer screen was updated. The text scrolls faster (which makes it begin to loop), and the default high score (or "hi score" in the original version) now has the name Doctor Robotnik rather than Eggman. The format for prize text is also slightly different, such as "FIGHTERS FEATHER GET" being changed to "YOU GET THE WARRIOR FEATHER." This may be a reference to Sonic the Fighters, which was the first game to feature the Piko Piko Hammer.
 * There are more robust features on the Internet for those who have their Dreamcasts online, with a functional Black Market exclusively on Japanese servers.
 * Some minor glitches were fixed, notably related to camera properties and occasionally collision detection. A miscellaneous example would be after Gamma completes Windy Valley; he spawns in front of the train station due to the fact that the other characters see the path to Angel Island open up from the train station.
 * Due to the game's engine being updated for the International audience, normal save files are incompatible with the previous version despite being a Dreamcast release. The A-Life files, however, are completely identical and are interchangeable between the two.

Sonic Adventure DX: Director's Cut
Sonic Adventure DX: Director's Cut (ソニックアドベンチャー デラックス), is a platform game for the GameCube and PC in 2004. It was also made available for the PlayStation 3, Xbox 360 and PC again in 2011 by download.

The game was released as an enhanced port of Sonic Adventure International for the Dreamcast, with several additional features added. The PC version was at first released only in Japan and Europe, but later saw a limited North American release. Sonic Adventure DX includes a mission mode, which included 60 missions to complete throughout the adventure fields and action stages. It also contains a minigame collection, which is comprised of twelve Game Gear games featuring Sonic and friends.

Reviews were generally less positive than those of its Dreamcast predecessor, scoring more than 20% lower than the original release.

Unlockable Games
Note: These are only available on the Nintendo Gamecube and the 2004 PC versions of this game.

The game features many unlockable games previously available on the Game Gear. If the start button of the second controller is pressed, the game screen will split, and two games will play at the same time. Additionally, Gear-to-Gear cable emulation is present, enabling the games that have two-player modes to be played if both players access the proper options within the game. These games were to be included in the Dreamcast version, but were scrapped due to time constraints. The same goes for the reintroduced feature of being able to play as Metal Sonic. A new Game Gear game is unlocked for every 20 Emblems the player gets, up until 100, then every 10 after that, or by completing 20 more of the 60 missions.

Unlockable games (in order):

 * 1) Sonic the Hedgehog (8-bit)
 * 2) Sonic Drift
 * 3) Sonic Chaos
 * 4) Sonic Labyrinth
 * 5) Sonic Spinball
 * 6) Sonic the Hedgehog 2 (8-bit)
 * 7) Dr. Robotnik's Mean Bean Machine
 * 8) Sonic Triple Trouble
 * 9) Sonic Drift 2
 * 10) Tails' Skypatrol
 * 11) Sonic Blast
 * 12) Tails Adventure

Changes Over the Original Sonic Adventure
Sonic Adventure DX: Director's Cut includes all of the basic alterations made to Sonic Adventure International as well as several additions/changes. They include:
 * Enhanced graphics: The main characters were redesigned with higher polygon counts and shading technology was also implemented for effects such as rippling water (shading effects were not present in the PC version, however).
 * The original 60 frame/s frame rate was restored. Unfortunately, due to the unstable nature of the Sonic Adventure engine, the game frequently skipped frames, usually in an uneven pattern (causing noticeable choppiness), even in places where few objects were displayed, and/or where the Dreamcast version did not slow down (however, some effects that caused slowdown before do not affect the frame rate in the GameCube version). Cutscenes ran at a lower frame rate, but this seemed to have been intended, for cinematic purposes.
 * Some sound effects, such as when collecting rings and emblems, were lower in pitch, while the losing rings sound effect was higher in pitch.
 * A Camera option was added to the pause menu, allowing the user to select either the original Auto Camera or the newly added Free Camera, which is usually closer to the character. In Auto Camera mode, the C-Stick can be used to get a first person view of the environment. In Free Camera mode, it rotates the camera around the player.
 * Changes (mostly minor) were made within the levels themselves in an effort to help solve some of the game's problems concerning collision detection. However, many glitches were not fixed, and some new ones were actually added. Some have to do with inconsistency in the port (for example, some windows still reflect the original Dreamcast graphics).
 * The Internet connection feature was removed. Very few of the downloadable content from the Dreamcast version, such as the Chao Garden's black market and additional voice packs, were included in the GameCube port. However, unlike the sequel, most of the online features were not incorporated into the GameCube game and remained exclusive.
 * Many changes to the Chao System were made, such as more interaction with the Chao, the ability to see their stats, as well as changes to the appearance of the Chao. The Chao Adventure VMU minigame was removed (instead replaced with a Game Boy Advance connection feature). The Chao System was overall very similar to the Sonic Adventure 2: Battle Chao System.
 * 60 Missions were added for an all-new Mission Mode, which tasks the player with completing certain goals within the Adventure Fields and Action Stages, similar to the Mission Mode found in Sonic Jam ' s three-dimensional Sonic World.
 * Metal Sonic becomes a playable character in Trial mode, as a reward for collecting all of the Emblems. He plays identically to Sonic, although his standing animation seems to be glitched. Oddly enough, he also cannot breath underwater.
 * Cream the Rabbit makes several cameo appearances during the main game and Mission Mode. She can be seen flying around Station Square.
 * As mentioned above, a Mini Game Collection mode was added allowing access to 12 Sega Game Gear games. This is the first time Sonic Drift and Tails' Skypatrol were released in the US and Europe.
 * The ability to skip cutscenes by pushing Start was added.
 * A map, found on the pause menu while in Adventure Fields, was added. This is especially useful when navigating the Mystic Ruins jungle.
 * The train used to transport from Station Square to Mystic Ruins is now blue instead of red as in the Dreamcast version.
 * Some voice effects were changed like when Tails begins to fly or when Amy swings her hammer.
 * The characters' mouth movements match up with their lines in each respective language. However, this seems to cause more graphical glitches (such as Tails sliding along the ground in Super Sonic's story in English). In Dreamcast versions, the lip-syncing did not match either language.
 * Loading times are significantly shorter than in the Dreamcast version.
 * In the opening title sequence, Tails has his mouth open when he flies by the shattering windows. His mouth is closed in the Dreamcast version.
 * Oddly enough, the final picture after each character's ending credits still reflects their Dreamcast designs.
 * Knuckles' purple eyes are more prominent like in official artwork.
 * Amy's boots are more rounded in the front, unlike the Dreamcast version where they were square-tipped.
 * The models of the characters in Sky Chase are now higher-poly.
 * In both the PC and GameCube versions, Sonic and Amy's eyelids are the same color as their fur unlike the Dreamcast version where they are the same color as their skin.
 * In the original, their hands were one solid object with lines in them, while in the port, their fingers are separated from each other.
 * The PC version does not include a variant of the Tiny Chao Garden, and instead has a generic Chao transporter.
 * Japanese language settings are set as the default in the Japanese region, which was not the case in Sonic Adventure International.

Steam, Xbox Live Arcade and PlayStation Network Port
Sega announced on 10 June 2010 that the game will be a downloadable title on the Xbox 360 and PlayStation 3 along with Crazy Taxi. Sonic Adventure was released on the Xbox Live Arcade and the PlayStation Network on 15 September 2010 for $10/£6.49; the DX content is available to add onto the game for an additional $5 (Currently, it's now US$4.99 for the Game and US$2.99 for the DX Upgrade). The upgrade also has somewhat upgraded graphics. However, the Game Gear games were removed from this version. Even without the DLC, it is essentially a variant of the PC port with locked content. It was later released on 5 March 2011 on Steam.

Differences

 * The cutscene in Super Sonic's Story when Sonic is at the burning altar is shown in a more cinematic style.
 * The graphics are brighter, with even shinier character models. Textures are more clear due to HD.
 * You can go online to view leaderboards.
 * The sound effects in the sound test menu respond better and are more organized.
 * The text font for the subtitles are different (due to being a port of the original PC release from 2004).
 * There are purple borders on each side of the screen (if played in widescreen), due to difficulties with making the game in true widescreen.
 * In Mission 12 for Knuckles the signs that had images of: Sonic Mega Collection, Sonic Advance 2 and Sonic Pinball Party now have images of Sonic 06, Sonic the Hedgehog 4: Episode I and Sonic Unleashed respectively.
 * The Game Gear games present in the 2004 PC version and the GameCube version were removed.

Downloadable Content
When Sonic Adventure was released on the Dreamcast, Sega regularly uploaded content onto the in-game site that would unlock already programmed, yet hidden, data. Sega had many downloads for Sonic Adventure as it was a launch title for Dreamcast as well as the Dreamcasts most popular game (selling 2.5 million copies as of June 2006). Most of these downloads were events and challenges that mostly took place in Station Square. These events were to celebrate an actual event or for competitions that were hosted by Sega.

Dreamcast Launch Party
"Welcome to the Dreamcast Launch! This is just the beginning."

- Message from poster.

One of the first things made available was the Dreamcast launch party in Station Square. Around the city, banners and balloons featuring the Dreamcast emblem and logo were set up and would thank people for supporting Sega and Sonic Team, as well as pointing out that there was plenty more in store. While the posters and language varied (Mainly Because of the Different Swirl Color), it is generally the same Dreamcast posters and balloons that thank you on behalf of Sega and Sonic Team when jumped at.

Halloween Party
"Halloween Party is being held at Twinkle Park now!"

- Message from poster.

From 19 October 1999 to 28 December 1999, Sega released Halloween decorations for Twinkle Park. Scattered around the level, graffiti has been tagged on the walls and floors wishing the players a Happy Halloween, while Jack-o-Lanterns in witch's clothing danced around. "Trick or Treat" would occasionally come up while walking on the graffiti. Station Square will have posters advertising Twinkle Park's Halloween party.

Christmas Party
"Merry Xmas!! Please keep in touch with Sonic."

- Message from tree.

From 17 December 1999 to 28 December 1999, this download places Christmas trees outside the station and also at the town center. Jumping at them will give a festive message as well as changing Station Square's theme to the Acapella version of Dreams, Dreams from Christmas NiGHTS into Dreams. Heading to the other parts of Station Square will reset its theme back to its usual theme.

Y2K Celebration
"A happy new year in 2K! Wish you a good new year!"

- Message from poster. "A happy new year in 2K! Please Support Sonic in 2K!"

- Message from poster.

With the year 2000 on the horizon, Sonic Adventure is given a Millennium Ring that floats around Station Square and two in several stages. Upon touching one, you are given a message wishing you a happy new millennium while being asked to support Sonic during that time. As this occurs, Palmtree Panic Zone's Japanese theme plays in celebration. There are also various posters around Station Square with the following messages: "Knuckles digging through 2K!", "Tails smiles through 2K!" and "Sonic runs through 2K!".

Samba GP
A new track was made available for download, titled the "Samba GP." The track was released to celebrate the arrival of Samba de Amigo although, oddly enough, the track had little to do with Samba de Amigo aside from the fact that the track uses an instrumental version of Sonic R's "Super Sonic Racing", which is a playable song in Samba de Amigo. Upon completing the track, you could save your score and upload it online to compare against others. Also worth noting is that this was the final update to the game that included any actual changes to the main game itself. Afterwards, Sega began to focus on Time Attack contests within the regular game itself.

Voice Packs
Files that allowed different character voices in the Menus. Files were released for Sonic, Tails, Knuckles, Amy, Big, E-102 Gamma, Dr. Eggman and Tikal.

AT&T/ODCM
AT&T and Official Dreamcast Magazine teamed up to release three time attack contests. One involved blazing through Speed Highway as Sonic, the next involving Knuckles collecting treasures in the Mystic Ruins and the final one involving Tails surfing through ten specially marked gates in Sand Hill. This was available only to the US. Prizes were awarded to the quickest scores. A total of fifteen winners would be awarded 1-Year long subscriptions to Official Dreamcast Magazine, nineteen winners would be awarded a Dreamcast game, and five would receive an AT&T Premium Package for a whole year free. It is likely the grand prize received all three. This contest ran from 29 October 1999 to 19 November 1999.

Reebok DMX Competition
Contestants from across Europe could download a specially designed version of Emerald Coast. Gamers are required to retrieve five pairs of hidden Reebok DMX trainers which Dr. Eggman has stolen from Sonic's wardrobe, while still competing for the fastest completion time. Times where then uploaded to Sega's servers so that contestants could gauge their rating. The winners would then be notified via e-mail and their names published on the Sonic Home Page and on Dreamarena at the end of the competition. The prizes included a personalized Dreamcast pod and £1,000 worth of Reebok sportswear. Neil Riddaway won the challenge by finishing in 46.09 seconds.

Christmas Trees in Station Square
Released sometime around the christmas season of 1998, this DLC scattered christmas trees around station square. Touching them would reveal a japanese message and various christmas songs, depending on what tree the player touches.

Hedgehog Hide and Seek
Released on 12 February 1999, Famitsu held a contest where players had to track down 5 pictures of actual hedgehogs that you must find around Station Square. To start the game, one must jump to the red sphere in front of the Train Station. Once all pictures are found you must go into the station and jump at the light blue sphere to finish the game.

Yukawa Senmu QUO MiniGame
The DLC consisted in using a character to run around Station Square and Mystic Ruins areas and try to collect 6 Mr. Yukawa cards (3 in each area) in the shortest time. This Was a promotion from 22 January 1999 to 22 February 1999 where 50 winners will get a 500 yen QUO card with a picture of Mr. Yukawa, (Yukawa Senmu, Senmu meaning the title of director or manager) the Sega manager on the Dreamcast box. The QUO card is a universal pre-paid card that can be used in 10,000 convenience stores and other locations in Japan.

Jewel Chao
Special Chao that were available in the Black Market in the Sonic Adventure WebPage. Only 3 were available for Sonic Adventure and only in Japan. They Were: Emerald Jewel Chao, Sapphire Jewel Chao, Ruby Jewel Chao.

Voice Pack (S.A. International)
A Special Version of the Voice Packs Released for Sonic Adventure International. The Main Difference Between the 2 in that this one includes every voice files compiled in one file. The various voices are activated randomly in the menus.

Comics
Archie Comics produced a tie-in story arc that began in Sonic the Hedgehog #79 and concluded in Sonic the Hedgehog #84, with the thirteenth Sonic Super Special, "Sonic Adventure", taking place in between.

Sonic the Comic also included a ten-issue, loose adaptation of the game, which was notably the final story arc ever produced for the series.

Sonic X
Sonic X included a Sonic Adventure adaptation between episode 27, "Pure Chaos" and episode 32, "Flood Fight". This adaptation was somewhat faithful to the story of the game, with the Japanese version even being a word-for-word adaptation at some points (the 4Kids version is somewhat less faithful to the game). However, parts were written in for characters that did not appear in Sonic Adventure such as Chris Thorndyke and Cream the Rabbit.

Trivia

 * Sonic X is loosely based on this game and has had its own arc in the anime.
 * This game marks the first appearance of Big the Cat, Froggy, Tikal, E-102 Gamma, Chaos and the Chao.
 * The Sonic Adventure games are considered to have been a sort of revamp of the Sonic the Hedgehog series due to the new character designs introduced, some of which differ greatly from the original designs (such as with Amy and Dr. Eggman). The "classic" designs are paid tribute, however, as slot machine and 1-up icons. Saturn models of Sonic and Tails were also intended to be used whilst piloting the Tornado according to pre-release screenshots, although this may have been a placeholder.
 * In the Mission Mode of Sonic Adventure DX, the player occasionally has to collect gold Sonic medals. Interestingly, these are the same gold Sonic medals from Sonic R.
 * Oddly enough, in the Casinopolis stage, if the player were to go into the bathroom and step into one of the shower stalls, Sonic will start to wash his quills for a few seconds.
 * When Amy is "remembering the good times" in a Sonic CD-inspired daydream, she is being rescued by Sonic while the two are chased by Metal Sonic. However, she is in her redesign instead of her old one. Interestingly, the backdrop resembles the original version of Windy Valley.
 * An unused line from Tikal states, "Gather 50 rings, and press the Action button while you jump. You'll transform into Super Sonic! But watch out for your ring consumption." which means that Super Sonic was originally going to be playable in the normal levels, much like he was in Sonic 2 and Sonic 3 &amp; Knuckles.
 * In the PC version of DX, there is a hack that makes this possible, if one were to have installed the hack, beaten Super Sonic's Story, then played any of Sonic's Action Stages.
 * Along with that, this feature may have been realized officially through unlocking Super Sonic in Sonic Generations, though only in the sense that you can play as him in Speed Highway.
 * When Big enters an elevator, he will say, "Ow!" when the doors close and since part of his tail is seen, it is obviously implying his tail got caught between the doors.
 * Sonic Adventure is the first Sonic game to feature downloadable content, as the Dreamcast was the first ever video game console to have online capabilities out of the box. DLC ranged from celebratory holiday decorations in the Adventure Fields and a few levels, such as on Christmas and Halloween, to national ranking contests and the addition of the Chao Black Market.
 * The game has sold over 2.5 million copies worldwide, making it the best-selling Dreamcast game.
 * In the original Dreamcast version of the game, if one were to insert the disk into a PC, special wallpapers hidden on the disk will be available for download. There is also a list of main console Sonic games prior to the release of Sonic Adventure (although Sonic CD is absent from the list). It reads:
 * SERIES TITLE:


 * SONIC the Hedgehog, 1991


 * SONIC the Hedgehog 2, 1992


 * SONIC the Hedgehog 3, 1994


 * SONIC and KNUCKLES, 1994


 * SONIC JAM, 1997


 * SONIC Adventure (for Japan), 1998


 * Cream the Rabbit makes cameo appearances in Sonic Adventure DX. She can be seen flying around Station Square when certain levels have been finished, or when a few special cutscenes have been played.
 * She also appears in the same manner in the Xbox Live Arcade version of Sonic Adventure even without having the DX DLC installed.
 * This is the first 3D main series Sonic game to feature Amy as a playable character.
 * In the Xbox Live Arcade and PlayStation Network versions, after performing specific tasks, clothes for PlayStation Home and Xbox 360 Avatars such as a Sonic Adventure T-Shirt and Sonic's shoes are available.
 * Sky Chase Act 1 was going to contain a two-headed dragon robot which would likely chase the Tornado toward the end of the level and act as a boss. It was scrapped, but it remains an unused asset in the game. Hacking in any version of the game can make it appear. Its programming is very limited and does not attack.Unused Dragon Boss Of Sonic Adventure
 * The game is noted to have many glitches, some of which allow characters access levels they normally can't play, such as Tails in Emerald Coast or Knuckles in Twinkle Park. This suggests that some of the characters, at one time, were intended to go into that stage.
 * When Sonic is on the Tornado, he has his original shoes on instead of the Light Speed Shoes, and is also missing his Crystal Ring (That is, if the player had acquired it).
 * The music in the beginning of Sonic's version of Twinkle Park borrows music from Panic Puppet Zone from the Mega Drive version of Sonic 3D.
 * In Windy Valley's last area, remixed Mega Drive music from Green Grove Zone is used. The latter was also in Sonic 3D.
 * The screenshots from the ending are from the initial Japanese release in all Dreamcast versions and the GameCube enhanced port in further re-releases.
 * Not counting the Sonic World in Sonic Jam, this is the first Sonic game to feature a hub world.
 * It was also the only Dreamcast Sonic game to have a hub world.
 * The PlayStation 3 version of the game is the first Sonic game to be on PlayStation Network.
 * This game is represented in Sonic Generations. Speed Highway reappears as the first stage of the Dreamcast Era in the home version, while Emerald Coast appears as the first stage in the portable version. Also, Perfect Chaos appears as the Gate Boss of the Dreamcast Era in the home version.
 * The playable story cast can be paired in groups based on their jumping method, ball or straight. Of those groups, both have the same missions, but with some slight differences:
 * Amy and Sonic both get to the goal, but Amy's missions have an invincible foe added in.
 * Knuckles and Big both hunt for something, but Big has to fish for his while Knuckles has to treasure hunt for it.
 * Tails and Gamma both have races; Tails has to race against another character while Gamma races against the clock to defeat his adversary.
 * This is the first Sonic game to have a different level entrance screen style. The other is Sonic Unleashed.
 * Since the level entrance screens are also loading screens, if you run the PC version of Sonic Adventure DX on a powerful computer, they appear for less than a second.
 * Some tracks in the wma files and sound test are not heard at points in the game where the name suggests it should play.
 * The Egg Carrier was meant to have a different track for when it had landed in the sea.
 * This track, however, is used during the cutscene when Gamma finds E-101 Beta as E-101 mkII.
 * Amy was meant to have a track named "Amy: Hurry Up", that supposedly was meant to have played when she was being chased by ZERO.
 * This track was instead used during the cutscene in Tails' Story when Eggman launches the Giant Missile on Station Square. (Since Amy was in the beginning of this cutscene, it could be named after Amy telling Tails to hurry up)
 * Many prototype images from the Dreamcast were re-used for the promotion of Sonic Adventure DX ' s.
 * Ryan Drummond said in an interview this is his favorite Sonic game.
 * The box of the PC version of Sonic Adventure DX: Director's Cut claims that this is "Sonic and friends' PC debut", but this is false. The first Sonic game on PC was Sonic CD.
 * During Super Sonic's ending, Knuckles is seen without his Shovel Claw and Tails is seen without his Rhythm Badge, despite both being mandatory to obtain in order to complete their stories and unlock Super Sonic's.
 * Although the game was originally released in 1998, one of the trailers of Sonic Generations lists its international release year (1999) as its official release year.
 * Hot Shelter is the only stage where Sonic is not playable in.
 * This game never had a 2D perspective part in the gameplay.
 * In the Sonic Adventure: DX version, when Amy is captured by Zero, you can see that she has her Dreamcast version design rather than her new design.
 * Tails and Knuckles do not share a stage with Amy.
 * Knuckles does not share a stage with Big as well.
 * Sonic Adventure was listed in the book 1001 Video Games You Must Play Before You Die, and in addition to that game, Sonic The Hedgehog (1991) and it's sequel were also listed.