StarCraft is a military science fiction real-time strategy video game developed by Blizzard Entertainment. The first game of the StarCraft series was released for Microsoft Windows on 31 March 1998. With more than 11 million copies sold worldwide as of February 2009, it is one of the best-selling games for the personal computer. A Mac OS version was released in March 1999, and a Nintendo 64 adaptation co-developed with Mass Media Interactive Entertainment was released on 13 June 2000. With its storyline adapted and expanded through a series of novels, StarCraft has three expansion packs available and a sequel in development, StarCraft II.