Call of Duty 4: Modern Warfare is the fourth installment of the main series, and was developed by Infinity Ward. It is the first game in the series not to be set during World War II, as well as the first to receive a Mature rating from the ESRB (except for the Nintendo DS version, which was rated Teen). The game was released for Microsoft Windows, Nintendo DS, PlayStation 3, and Xbox 360 on November 7, 2007. Download and retail versions for Mac OS X were released by Aspyr in September 2008. As of May 2009, Call of Duty 4: Modern Warfare has sold over 13 million copies. ---------------------- Call of Duty: Modern Warfare 2 is the sixth installment of the main series. It was developed by Infinity Ward and published by Activision. Activision Blizzard officially announced Modern Warfare 2 on February 11, 2009. The game was released worldwide on November 10, 2009, for the Xbox 360, PlayStation 3 and Microsoft Windows. A Nintendo DS iteration of the game, titled Call of Duty: Modern Warfare: Mobilized, was released alongside the game and the Wii port of Call of Duty : Modern Warfare. Modern Warfare 2 is the direct sequel to Call of Duty 4 and continues the same storyline, taking place five years after the first game and featuring several returning characters including Captain Price and "Soap" MacTavish. ---------------------- Call of Duty: Black Ops is a 2010 first-person shooter video game developed by Treyarch and published by Activision for release on November 9, 2010. Officially announced on April 30, 2010, the game is the seventh installment of the Call of Duty series and the third game in the series to be developed by Treyarch. It was initially only available for pre-order on PC, Xbox 360, and PlayStation 3; however, Activison has since confirmed that it will also be released for the Nintendo Wii as well as the Nintendo DS.