This article is about a subject in the real world. Information in this article is about real-life people, companies and objects, and does not relate to the in-universe Sonic series.
The Dreamcast was the last video game console to date manufactured by Sega. It was released before its contemporary consoles (the Nintendo GameCube, PlayStation 2 and Xbox), but competition with these platforms meant that it failed to generate sufficient revenue and Sega eventually withdrew from the console market altogether. It had a short life, being released in 1998 in Japan and 1999 in the West (North America, Europe and Australia) and then discontinued (in North America) in 2001, Europe and Australia in 2002 and Japan in 2007. It is now available only on the Internet and independent small stores.
Using a Dreamcast emulator and a ROM, one can play Dreamcast games on a computer. The Dreamcast GD-ROM is also close to the size of a compact disc and can be inserted into the computer to access bonus content (e.g. special pictures in Sonic Adventure).
Sonic Generations Dreamcast Era
Stages from Sonic Adventure and Sonic Adventure 2 were in Sonic Generations. Despite Sonic Heroes not being a Dreamcast game it was added as the "third Dreamcast game" so that each era has three games represented and also, it was part of the 6th-generation console era along with the PlayStation 2, Xbox and Nintendo GameCube.
The swirl was orange in Japan and red in North America. However, the swirl had to be changed to blue in Europe and Australia because of copyright reasons as a German company, Tivola used a similar red swirl and Sega would have gotten into litigation for copyright infringement.
In the Eggmanland hub in Sonic Unleashed, Sonic will meet a robot named EF-DC1998 making reference to the Dreamcast and it says he has a model mainstay just like the Dreamcast.
This console (and the Sega Saturn) has the fewest Sonic games for a Sega console.