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.
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.