Call of Duty is a 2003 first-person shooter video game developed by Infinity Ward and published by Activision. It is the first installment in the "Call of Duty" franchise, released on October 29, 2003, for Microsoft Windows. The game simulates infantry and combined arms warfare of World War II using a modified version of the id Tech 3 engine. Much of its theme and gameplay is similar to the "Medal of Honor" series; however, "Call of Duty" showcases multiple viewpoints staged in the British, American, and Soviet theaters of World War II.