Many features were added and changed from the original Call of Duty, notably regenerating health and an icon that indicates a nearby grenade about to explode. It contains four individual campaigns, split into three stories, with a total of 27 missions. The game is set during World War II and the campaign mode is experienced through the perspectives of four soldiers: one in the Red Army, one in the United States Army, and two in the British Army. Other versions were eventually released for OS X, mobile phones, and Pocket PCs. Announced by Activision on April 7, 2005, the game was released on Octofor Microsoft Windows, and on Novem as a launch title for the Xbox 360. It is the second installment of the Call of Duty series. Call of Duty 2 is a 2005 first-person shooter video game developed by Infinity Ward and published by Activision in most regions of the world.