Sonic Adventure (ソニックアドベンチャー, Sonikku Adobenchā?) is a video game developed by Sonic Team and released on December 23, 1998 in Japan by Sega for the Sega Dreamcast and it is the first game in the Sonic Adventure series with the Chao-breeding simulation and the mini games. Sonic offers much more beyond the completion of its story.
A director's cut version was released in 2003 as Sonic Adventure DX for the Nintendo Game Cube and in 2004 for Microsoft Windows. It has sold over 1 million copies in the United States alone, making it the top selling Dreamcast game. It was the first Sonic game on a sixth generation console. Its sequel is Sonic Adventure 2.