Sonic Adventure (Japanese: ソニックアドベンチャー, Sonikku Adobenchā) is a 1998 Action Platform video game by SEGA, for the Dreamcast, being the first Sonic game released on the system. It was later re-released on GameCube and Microsoft Windows as Sonic Adventure DX: Director's Cut, which included bonus content and updated graphics. Development was supported by NOW Production. A high-definition update was also released in 2010 on Xbox Live Arcade and the PlayStation Store.
Each character has their own story, however, they collide at numerous points. Sonic's story starts off with him in a blocked off portion of the city, fighting a creature known as "Chaos". After beating it, a cutscene plays, which shows Sonic enjoying the beach, relaxing on a sunbathing chair. He notices Tails flying above, however, his plane begins to sputter and ultimately crashes somewhere along the coast. Sonic finds him, and the duo head back to the pool area. Tails laughs it off, saying he was trying out a new fuel source: the chaos emerald. He then invites Sonic over to his workshop where he is approached by Dr. Eggman and fights his machine: The EGG HORNET. After defeating Dr. Eggman, a stone appears in front of Tail's workshop, which is the key to unlock the level Windy Valley.
There are 3 main hub worlds in this game, they are:
However, you will spend most of your time at Station Square and Mystic Ruins.
- Sonic the Hedgehog
- Amy Rose
- Big the Cat
- E102 Gamma
- Super Sonic - Unlocked when the player completes the game with the other characters.
- Metal Sonic - (DX exclusive) - Unlocked when the player earns all 130 emblems.
Each character has certain levels available to them, and each character has a specific goal:
*Sonic - Reach the end of the level and rescue the animals from the capsule (a homage to the original Sonic the Hedgehog) *Tails - Beat Sonic to the end of the level.
- Knuckles - Find the three pieces of the Master Emerald.
- Amy - Escape from the mechanical robot.
- Big - Find froggy.
- E-102 Gamma - Destroy the target.
- Emerald Coast
- Windy Valley
- Ice Cap
- Sky Chase Act I
- Twinkle Park
- Speed Highway
- Red Mountain
- Sky Chase Act II
- Sky Deck
- Lost World
- Final Egg
Note: The Mini-Game collection was omitted from the HD versions, for unknown reasons. It was to be included in the Dreamcast version but was removed due to time constraints.
- Sonic the Hedgehog (8-bit)
- Sonic Drift
- Sonic Chaos
- Sonic Labyrinth
- Sonic Spinball
- Sonic the Hedgehog 2 (8-bit)
- Dr. Robotnik's Mean Bean Machine
- Sonic Triple Trouble
- Sonic Drift 2
- Tails' Skypatrol
- Sonic Blast
- Tails Adventure
Reception & Legacy
Sonic Adventure was very popular, and sold 2.5 million units, making it the best selling Dreamcast game. 
|Title||Image||Description||Reward [Note 1]|
|Miles "Tails" Prower||Become friends with Tails.||Bronze / 10G|
|Knuckles the Echidna||Become friends with Knuckles.||Bronze / 10G|
|Amy Rose||Become friends with Amy.||Bronze / 10G|
|E-102 "γ"||Become friends with E-102.||Bronze / 10G|
|Big the Cat||Become friends with Big.||Bronze / 10G|
|Sonic the Hedgehog||Clear the Sonic story.||Bronze / 10G|
|Super Sonic||Clear all characters stories.||Bronze / 20G|
|The Fastest & Strongest||Get Level A on all the Action Stages.||Silver / 20G|
|Sub Game Master||Get all Emblems of the Sub Games.||Silver / 20G|
|Chao's Best Friend||Get all Emblems of the Chao Race.||Silver / 20G|
|The Adventurer||Get all Emblems in the Adventure Field.||Silver / 20G|
|The Perfect Adventurer||Get 130 Emblems.||Gold / 40G|
|Title||Image||Description||Reward [Note 1]|
|Metal Sonic||Get all 130 Emblems by playing Sonic Adventure DX.||Bronze / 15G|
|Metal Sonic Master||Get Level A on all the Action Stages by using Metal Sonic.||Silver / 15G|
|Mission All Accomplished||Clear all 60 missions.||Gold / 20G|
- The game is notable for being very glitchy, allowing speedrunners to finish the game in just 40 minutes.
- There's a strange glitch were other characters can access stages that they weren't originally meant to enter. They don't spawn where Sonic spawns however, potentially indicating that the levels were intended to be playable by these characters.
- An unused Dragon Boss was found in the game's files. A demonstration can be found here
- In the game's files, it is possible to find the game's characters saying things such as "Sonic Team" and "SEGA"
- Speed Highway made an appearance in Sonic Generations.
- Hot Shelter is the only level that cannot be played as Sonic
- Achievements were recently introduced into the Steam version, however are not yet working as of September 2014. Online Leaderboards are also absent.
- There are purple boarders on the game screen on the HD port, due to programming difficulties.
- Online features were absent from the GameCube version, despite being included in the Dreamcast.
- Cream the Rabbit makes multiple appearances, notably after the player leaves Casinopolis, and shortly after Amy's story begins.
- NiGHTS makes a cameo in the Casinopolis stage.
- Sonic Adventure was the first Sonic game to have downloadable content, see Sonic Adventure/DLC for a full list.
- The game was originally titled Sonic RPG and was to be released on the Sega Saturn
- It was originally intended for you to be able to play as Super Sonic during levels. Mods make this possible, however. [Note 2]
- It was intended that Station Square would be connected, as you can see an untextured, hovering portion of the Casino Area in the debug mode [or by glitching out of the map, as demonstrated below].
- The train in Station Square was originally meant to leave and return periodically, hence the "train to Station Square/Mystic Ruins is departing soon" dialogue.
- Windy Valley was completely different in the Beta version, and there are mods which reconstruct it.
- Amy and Big were originally playable in the level, potentially meaning all characters could play the stage.
- Knuckles was originally able to uppercut. This was removed from the full game for unknown reasons.
- Emerald Coast experienced minor changes.
- The chase with Orca originally had no dash-pads.
- In Big's level, Froggy was originally located in a secret passage.