Sonic Adventure

Sonic Adventure is a 3D Sonic the Hedgehog game for the Sega Dreamcast that was released in 1998. This was Sonic's first true transistion to the 3D world. As the Sega Dreamcast needed awesome launch titles, Sonic Advneture was made. Sega put a lot of effort into the game, and despite it not being entirely finished, many hail it as one of Sonic's finest games. 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.

Gameplay
In the game you can play as Sonic, Tails, E-102 Gamma, Knuckles, Big the Cat, and Amy. The game is completely in 3D. The way that the game works is you start out in a hub world. The hub worlds connect to the games levels, boss fights, and the choa worlds. You can also go around the hub world and talk with the civilians. The way you get upgrades is by finding them in the hub world.

Sonic's stages are high speed platforming. Sonic's stages are about being fast. Tail's stages are about outrunning either Sonic or Doctor Eggman. Knuckles stages are about finding the Master Emerald. So that means that Knuckles stages are treasurer hunting. Amy's stages are slow platforming. Amy is one of the slower characters. Big the Cat's stages are all about fishing/finding Froggy. E-102 Gamma's stages are also  slow platfroming.

Sonic begins the game with the Homing Attack, his unlockable abilities are Light Speed Dash,

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.

Sonic Adventure DX Directors Cut
There are many differences between the two versions, in DX, there is a mission mode when you finnish the whole story of a character, it consists of 60 missions which you compleate by doing different tasks in the adventure and action stages. There is also the minigame collection when you collect a certain amount of emblems in the game.