Sonic Adventure is a 3D platformer video game in the Sonic the Hedgehog series. The player can control six characters from the Sonic universe, each with their own gameplay and point of view of the story. The game is divided up into two types of levels: Action Stages and Adventure Fields. The division of Action Stages and Adventure Fields are a serious departure from all previous Sonic games. Adventure Fields are non-linear game stages that contain very few items, generally designed for puzzle solving, exploration and plot advancement. Action Stages are more speed based and have Rings scattered in them. Sonic Adventure was the top-selling Dreamcast game and received a sequel in 2001, marking the 10th anniversary of the Sonic the Hedgehog series.