CD
The Sega CD was an add-on released for the Sega Genesis in the early 1990s—1991 in Japan and the following year in North America. As its name might suggest, the Sega CD allowed the Genesis to run CD-based games in addition to traditional Genesis cartridges. A new CPU was included as part of the Sega CD that allowed the more advanced CD-based games to operate. While the Sega CD was not a widely successful system—it sold just over 2.2 million units worldwide—it did feature several popular games. Sonic CD, Shining Force CD, Star Wars: Rebel Assault, The Secret of Monkey Island, and the controversial Night Trap all remain noteworthy Sega CD titles. Production of the Sega CD continued until 1996, a year after the Sega Saturn was released.