Call of Duty 4: Modern Warfare is a first-person shooter developed by Infinity Ward and published by Activision. An installment in the Call of Duty series, it was released in November 2007 for the PlayStation 3, Xbox 360, and Microsoft Windows. The game breaks away from the World War II setting of previous entries in the series and is instead set in modern times. Developed for over two years, the game uses a proprietary game engine. The story takes place in the year 2011, where a radical leader has executed the president of an unnamed country in the Middle East, and an ultranationalist movement ignites a civil war in Russia. The conflicts are seen from the perspectives of a U.S. Force Reconnaissance Marine and a British SAS commando, and are set in various locales, such as the United Kingdom, the Middle East, Azerbaijan, Russia, and Ukraine. The multiplayer portion of the game features various game modes, and contains a leveling system that allows the player to unlock additional weapons, weapon attachments, and camouflage schemes as they advance. The game received universal acclaim from critics, with the gameplay and story receiving particular praise, while criticism targeted the failure of the game to substantially innovate the first-person shooter genre. The game won numerous awards from gaming websites, including IGN's Best Xbox 360 Game. It was the top-selling game worldwide for 2007, selling around seven million copies by January 2008 and almost sixteen million by November 2013. It was followed by two sequels that continue the storyline: Call of Duty: Modern Warfare 2 and Call of Duty: Modern Warfare 3. A remastered version of the game, Call of Duty: Modern Warfare Remastered, was released on PlayStation 4, Xbox One and PC alongside special editions of Call of Duty: Infinite Warfare in November 2016. A standalone version was released in June 2017.