Story: SA2 introduces two new playable characters to the Sonic universe: Rouge the Bat and Shadow the Hedgehog. By introducing these characters, there is a good guy (hero) for every bad guy (dark). Instead six separate story lines as in the first Sonic Adventure, there are only two sides to the story: a hero side and a dark side. Characters take turns exploring different levels, and cut scenes connect the levels with the story.
The hero story begins when Sonic is detained by G.U.N., a military force. Sonic escapes and meets Shadow, who uses a Chaos Emerald to warp quickly. Sonic soon discovers a connection between Eggman and Shadow, and he sets out to put an end to their plan with Tails and Knuckles.
The dark story begins Eggman discovers Shadow, the "ultimate life form." Shadow and Eggman plot to use the Eclipse Cannon to take over the world, and Rouge assists them.
Levels: The types of levels are pretty basic. Sonic and Shadow have fast action stages, which involves running. Knuckles and Rouge hunt in each stage for pieces of the shattered Master Emerald. Tails and Eggman use their machines to shoot their way through each stage.
| Hero story levels (and the playable character): | Dark story levels (and the playable character): |
| City Escape (Sonic) Wild Canyon (Knuckles) Prison Lane (Tails) Metal Harbor (Sonic) Green Forest (Sonic) Pumpkin Hill (Knuckles) Mission Street (Tails) Aquatic Mine (Knuckles) Route 101 (Tails) Hidden Base (Tails) Pyramid Cave (Sonic) Death Chamber (Knuckles) Eternal Engine (Tails) Meteor Herd (Knuckles) Crazy Gadget (Sonic) Final Rush (Sonic) |
Iron Gate (Eggman) Dry Lagoon (Rouge) Sand Ocean (Eggman) Radical Highway (Shadow) Egg Quarters (Rouge) Lost Colony (Eggman) Weapons Bed (Eggman) Security Hall (Rouge) White Jungle (Shadow) Route 280 (Rouge) Sky Rail (Shadow) Mad Space (Rouge) Cosmic Wall (Eggman) Final Chase (Shadow) |
The final level, Cannon's Core, involves most of the hero and dark characters and is unlocked after all hero and dark stages are complete.
Chaos Emeralds: The seven Chaos Emeralds do appear in the game, but they are collected as the plot progresses rather than entering a special stage. At the end of the game, Super Sonic and Super Shadow use the power of the emeralds to defeat the Final Hazard.
The Master Emerald also appears in the game, and the pieces of the shattered emerald must be found.
Miscellaneous: There are a few differences between SA2 and Sonic Adventure. Changes that have been made include: the deletion of the Adventure Fields, a new two-player mode, different kart racing, and more intelligent Chao, just to name a few.
For each stage, there are five missions to complete. The purpose of the first mission is to clear the stage. For the second mission, you must collect 100 rings. To complete the third mission, you must find the lost Chao. The fourth mission is to clear the stage within a specified amount of time. The final mission is to beat a harder version of the stage. Upon completion of each mission, a rank is assigned to rate your performance. An "A" means that you have mastered the stage, while "E" can be jokingly translated as "excellent, you passed the stage!"
Your efforts to clear every mission do not go unnoticed. Once all of the missions have been completed for a character, a new costume is available in two-player mode. But you can't stop earning emblems there. After the all A-rank emblem has been earned for a character, a new character is unlocked in two-player mode. There are a total of 180 emblems. If all emblems are earned, a bonus stage is unlocked: Green Hill from the original Sonic the Hedgehog game. The environment has been changed so that Sonic now plays in a 3-D Green Hill.
Sonic Adventure 2 was later re-released
for the Nintendo GameCube as Sonic Adventure 2 Battle,
with a few new additions and changes.