It ended up only lasting about ten seconds, and we knew we couldn't build a game around this structure. When we built our first test level, we knew we had to test it out, just to make sure our ideas worked. It was also decided that it would also have a much greater focus on plot. Takashi Iizuka, Senior Game Designer for Sonic the Hedgehog 3, Sonic & Knuckles and current head of Sonic Team initially wanted to make an RPG, but it was later decided to have the next main Sonic game be a 3D platformer. The conceptualization of Sonic Adventure began sometime after the completion of NiGHTS into Dreams. September 9 - Sonic Adventure is released in North America.December 23 - Sonic Adventure is released in Japan.
October 5 - A special AutoDemo version is sent to Japanese retailers to promote the game, with several files still leftover from the September 1998 build.September - An unknown version is built, presumably for gameplay demo purposes.August 22 - The game was revealed at the Tokyo International Forums.May - Screenshots of a new Sonic game were released, which at first were believed to be fake, but later true.June 20 - Sonic Jam is released for the Sega Saturn, which contains elements from the then-forthcoming Sonic Adventure.March/April - An internal contest is held at Sega to redesign Sonic The Hedgehog.November - The Sega Saturn port of Sonic 3D Blast is released which contains 3D Special Stages made by Sonic Team themselves and contains assets from the soon to be Sonic Jam, and by extension Sonic Adventure.July - Sonic Adventure is conceptualized and starts development after the completion of NiGHTS into Dreams., where the developers wanted to make it a greater focus on the plot.