Sonic Adventure 2 is a 2001 platform video game developed by Sonic Team USA and published by Sega. It was the final Sonic the Hedgehog game for the Dreamcast after Sega left the home console market. It features two good-vs-evil stories: Sonic the Hedgehog, Tails and Knuckles the Echidna attempt to save the world, while Shadow the Hedgehog, Doctor Eggman and Rouge the Bat attempt to conquer it. The stories are divided into three gameplay styles: fast-paced platforming for Sonic and Shadow, multi-directional shooting for Tails and Eggman, and action-exploration for Knuckles and Rouge. Development began soon after the American release of Sonic Adventure in 1999 and lasted 18 months. The game was produced in commemoration of the Sonic series' tenth anniversary and was designed to be faster-paced and more action-oriented than the original. The development team also expanded upon the presence of the Chao creatures and other player characters. Its locations were influenced by American locations such as San Francisco and Yosemite National Park. Sega announced Sonic Adventure 2 in October 1999 and exhibited it at E3 2000. It was released in North America on June 19, 2001, and in Japan and Europe on June 23, 2001. Sonic Adventure 2 received generally positive reviews for its gameplay variety, visuals, and audio, though some criticized its camera, voice acting, and plot. An enhanced port for the GameCube, Sonic Adventure 2: Battle, was released late 2001 in Japan and early 2002 in North America and Europe; it features improved textures and multiplayer options. Together, the Dreamcast and GameCube sold more than 2 million copies worldwide. Sonic Adventure 2 was also released as a downloadable game for the PlayStation 3, Xbox 360, and Windows in 2012.