Adventure Field

Adventure Fields are the hubworlds of Sonic Adventure. These are not traditional Sonic levels, containing neither linear path(s) nor a concrete objective, but rather they connect the traditional levels (Action Stages) to each other and the Chao Gardens, as well as being the setting for various sidequests and boss fights. In this way Sonic Adventure incorporated RPG elements on top of the standard fare of high-speed platforming.

There were three seperate Adventure Fields in Sonic Adventure, namely:

• Station Square, a bustling human city - leads to Emerald Coast, Casinopolis, Twinkle Park and Speed Highway
• Mystic Ruins, ancient temples in the jungle - leads to Windy Valley, Ice Cap, Sky Chase Acts 1 and 2, Red Mountain, Lost World, Final Egg, and Sand Hill.
• Egg Carrier, Eggman's vast flying fortress - leads to Sky Deck and Hot Shelter

• 

  Station Square

• 

  Mystic Ruins

• 

  Egg Carrier

Transit between these hubworlds, and accessing different locations within them, became easier as the game progressed, with power-ups and plot events opening up more areas.

The strategy of using Adventure-Field-like hubworlds has reappeared in several other Sonic games, notably Sonic '06 and Sonic Unleashed.