The Sega CD, known as Mega-CD in most regions outside North America and Brazil, is a CD-ROM accessory and format for the Sega Genesis produced by Sega as part of the fourth generation of video game consoles. Originally released in November 1991, it came to North America in late 1992, and the rest of the world in 1993. The Sega CD plays CD-based games and adds hardware functionality such as a faster CPU and a custom graphics chip for enhanced sprite scaling and rotation. It can also play audio CDs and CD+G discs.
Sega sought to match the capabilities of the competing PC Engine CD-ROMĀ² System, and partnered with JVC to design the Sega CD. Sega refused to consult with their American division until the project was complete, fearful of leaks. The Sega CD was redesigned several times by Sega and was also licensed to third parties, including Pioneer and Aiwa who released home audio products with Sega CD gaming capability. The main benefit of CD technology at the time was greater storage; CDs offered approximately 160 times more space than Genesis/Mega Drive cartridges. This benefit manifested as full-motion video (FMV) games such as the controversial Night Trap.
The Sega CD game library features acclaimed games such as Sonic CD, Lunar: The Silver Star, Lunar: Eternal Blue, Popful Mail, and Snatcher, but also many Genesis ports and poorly received FMV games. Only 2.24 million Sega CD units were sold, after which Sega discontinued it to focus on the Sega Saturn. Retrospective reception has been mixed, with praise for some games and functions, but criticism for its lack of deep games and its high price. Sega's poor support for the Sega CD has been criticized as the beginning of the devaluation of its brand.