Sonic Adventure

Sonic Adventure is a 1998 platform game for Sega's Dreamcast and the first main Sonic the Hedgehog game to feature 3D gameplay. The story follows Sonic the Hedgehog, Miles "Tails" Prower, Knuckles the Echidna, Amy Rose, Big the Cat, and E-102 Gamma in their quests to collect the seven Chaos Emeralds and stop series antagonist Doctor Robotnik from unleashing Chaos, an ancient evil. Controlling one of the six characters—each with their own special abilities—players explore a series of themed levels to progress through the story. Sonic Adventure retains many elements from prior Sonic games, such as power-ups and the ring-based health system. Outside the main game, players can play minigames like racing and interact with Chao, a virtual pet.

Following the cancellation of the Sega Saturn game Sonic X-treme, Sonic Team began work on Sonic Adventure in 1997, drawing inspiration from locations in Peru and Guatemala. Yuji Uekawa redesigned the characters for their transition to 3D, and features were added to take advantage of the Dreamcast hardware. Sega announced the game in August 1998; it was released in Japan that December and worldwide in September 1999. Sonic Adventure was ported to the GameCube and Windows in 2003 as Sonic Adventure DX: Director's Cut, featuring updated graphics and more challenges. A high-definition version was released digitally for the PlayStation 3 and Xbox 360 in 2010, and for Windows in 2011.

Sonic Adventure received critical acclaim and, with 2.5 million copies sold by August 2006, became the Dreamcast's bestseller. Reviewers lauded the visuals and gameplay, calling it a major technological advancement; some speculated that it could re-establish Sega as the dominant console manufacturer after the relatively unsuccessful Saturn. Others were frustrated by the camera controls and glitches, and reactions to its audio were mixed. Reviews for later releases were less positive; critics felt the game had not aged well and ran at an inconsistent frame rate. Despite this, journalists have ranked Sonic Adventure among the best Sonic games, and it is recognized as an important release in both the series and the platform genre. A sequel, Sonic Adventure 2, was released in 2001.