Sega Enterprises Ltd. v. Accolade, Inc.
977 F.2d 1510 (9th Cir. 1993) - full text opinion
Ishido, the first game Accolade ported to the Sega Genesis, is, despite its name, not an ancient Japanese pastime. Rather, it was developed in 1990 as a type of tile matching game. First released for MS-DOS and Macintosh, Accolade was able to produce a version for the Genesis through reverse-engineering. (If you'd like to know more about how reverse-engineering works, start here).
All versions of the game have now fallen out of print, and the Macintosh version has been made freely available by its programmer.
Accolade was well known in the late 1980's for producing high quality video games. However, the company hit hard times in the late 1990's, and was eventually sold to Infogrames/Atari. Sega was never able to replicate the success it achieved with the Genesis. Its two later consoles, the Saturn and the Dreamcast, were both commercial disappointments. In 2001, Sega stopped producing consoles altogether, and now focuses on game development.