Call of Duty 4: Modern Warfare is a first-person shooter developed by Infinity Ward and published by Activision for PC, Nintendo DS, Playstation 3 and Xbox 360. It is the fourth installment in the Call of Duty video game series (excluding expansions), the first not to be set during World War II, and the first game in the series to be rated Mature. It was announced on April 25, 2007.[4] It was released on November 6, 2007 in North America, on November 7, 2007 in Australia, and on November 9, 2007 in Europe. The game also became available on Steam on November 6, 2007 for pre-purchase and was available to play as of November 12, 2007.