Call of Duty 4: Modern Warfare is a 2007 video game developed by and published by . It is the fourth main installment in the . The game breaks away from the setting of previous entries and is instead set in modern times. Developed for over two years, Modern Warfare was released in November 2007 for the , and , and was ported to the as Call of Duty: Modern Warfare – Reflex Edition in 2009.
The story takes place in the year of 2011, where a radical leader has executed the president of an unnamed country in the , and an movement ignites a in Russia. The conflicts are seen from the perspectives of a sergeant and a commando and are set in various locales, such as the United Kingdom, the Middle East, Azerbaijan, Russia, and Ukraine. The portion of the game features various and contains a leveling system that allows the player to unlock additional weapons, weapon attachments, and camouflage schemes as they advance.
Call of Duty 4: Modern Warfare is a . 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.
The game is the first in the to feature modern equipment. The game also introduces new features, particularly multiplayer mechanics such as "killstreaks" where the player gains access to special abilities for killing enemies without dying.