Call of Duty 4: Modern Warfare is a 2007 first-person shooter video game, developed by Infinity Ward and published by Activision for Microsoft Windows, Mac OS X, PlayStation 3, Xbox 360 and Wii. A handheld game was made for the Nintendo DS. The game was released in North America, Australia, and Europe in November 2007 for video game consoles and Microsoft Windows. It was released for the Mac in September 2008, then released for the Wii in November 2009, given the subtitle Reflex Edition. It is the fourth installment in the Call of Duty video game series, excluding expansion packs, and is the first in the Modern Warfare line of the franchise, followed by a direct sequel, Call of Duty: Modern Warfare 2 as well as the first game in the series to have a Mature rating. The game breaks away from the World War II setting of previous games in the series and is instead set in modern times. Developed for over two years, the game uses a proprietary game engine. On September 10, 2009, it was re-released in Japan by Square Enix.
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 starts 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.
Critically acclaimed, the game received an aggregated score of 94% from both GameRankings and Metacritic, and is considered by many to be the best Call of Duty in the series. The gameplay and story received 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 over thirteen million by May 2009.

Gameplay
As opposed to earlier games in the Call of Duty series, the game features modern equipment and new features, many exclusive to the multiplayer part of the game, such as 'killstreaks'; killing a number of enemies without the player dying in between kills allows access to various assets including airstrikes and helicopter support. A character can be positioned in one of three stances: standing, crouching, or prone; each affecting the character's rate of movement, accuracy, and stealth. Using cover helps the player avoid enemy fire or recover health after taking significant damage. As such, there are no armor or health power ups. When the character has taken damage, the edges of the screen glow red and the character's heartbeat increases. If the character stays out of fire, the character can recover. When the character is within the blast radius of a live grenade, a marker indicates the direction of the grenade, helping the player to either flee or toss it back to the enemy.