The Sega 32X , codenamed Project Mars, is an add-on for the Mega Drive/Genesis video game console by Sega.
In Japan, it was distributed under the name Sega Super 32X. In North America, its name was the Sega Genesis 32X. In Europe, Australia, and other countries that use PAL, it was called the Sega Mega Drive 32X.
With the release of the Super Famicom in Japan and the Super NES in North America, Sega felt the need to leapfrog Nintendo in the technological department. The Sega Mega-CD, known as Sega CD in North America, had not worked as well, in a business sense, as Sega had wanted it to. Sega had various developments underway, and focused most of its energy on the then-new Sega Saturn. Some used System 16 technology, as the Mega Drive/Genesis and other arcade games did.
The 32X was released in mid-November 1994 in North America for US$159, Japan on December 3, 1994 for ¥16,800, and Europe in January 1995 for £170 / DM400.
Source: Wikipedia, "Sega 32X", available under the CC-BY-SA License.