Sonic Adventure, released for the Dreamcast in 1998 in Japan and 1999 elsewhere, is a pivotal 3D platformer in the Sonic the Hedgehog series. It signifies Sonic's transition into a fully 3D environment, following his fast-paced, ring-collecting adventures across various expansive levels. Players experience multiple characters' perspectives and abilities, all while battling the nefarious Dr. Eggman. The game incorporates a mix of action, platforming, and exploration, and introduces the Chao garden mini-game for added depth.