Call of Duty 4: Modern Warfare is a 2007 first-person shooter video game developed by Infinity Ward and published by Activision.

The story takes place in the year of 2011 when 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. Marine Force Recon sergeant and a British SAS commando and are set in various locales, such as the United Kingdom, the Middle East, Azerbaijan, Russia, and Ukraine.

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.

The mission itself has no bearing on the campaign plot and focuses on a SAS squad fighting terrorists that have hijacked an airplane and taken a VIP hostage.

The main campaign features 30 collectible pieces of intel that award the player with game cheats and visual filters such as infinite ammunition, cluster grenades, and increased contrast.

[2] Players can call in UAV reconnaissance scans, airstrikes, and attack helicopters when they achieve three-, five-, and seven-enemy kill streaks respectively.

If the points are even when the time expires, Sudden Death mode is activated in which there is no re-spawning, and the team that either has the last man standing or achieves the objective first is the winner.

[3] As the player advances in levels and goes up higher in prestige, they earn the ability to customize their classes; this includes selecting their main weapon, sidearm, and special grenade type.

[4] Sergeant Paul Jackson is a member of the U.S. Marine Corps 1st Force Recon Company deployed to an unnamed Middle Eastern country.

[2][4][5] The game's non-playable characters (NPCs) feature prominently in the story: Captain Price and his second-in-command, Gaz (Craig Fairbrass), serve as mentors to Soap.

Meanwhile, a separatist group led by Khaled Al-Asad, who holds anti-Western views, seizes power in an unnamed country in the Middle East through a coup d'état.

A platoon of U.S. Marines from 1st Force Recon Co, led by Lieutenant Vasquez, fail to capture Al-Asad and later engage in urban combat in a nearby city with support from an M1 Abrams tank.

Price reveals that in the aftermath of the Chernobyl disaster and the collapse of the Soviet Union, Zakhaev profited from nuclear proliferation and used his new wealth to lure ex-Soviet military personnel to form his Ultranationalist party.

However, Zakhaev promptly launches nuclear intercontinental ballistic missiles at the U.S. Eastern Seaboard, with the potential of causing 41 million casualties.

In the epilogue, the missile incident and the Ultranationalists' support of Al-Asad are covered up, prompting the events in Call of Duty: Modern Warfare 2.

After Call of Duty 2, the Infinity Ward team decided to move away from the World War II environment of previous games in the series.

While developing the story for Call of Duty 4, Infinity Ward chose to avoid referencing current, real-life wars, and keep the series' common theme of two opposing forces of similar strength.

To enhance the realistic feel of the game, the development team attended a live-fire exercise at Marine Corps Air Ground Combat Center Twentynine Palms, a training facility in the California desert.

Several music tracks from the game are available on Infinity Ward's "7 Days of Modern Warfare" website, and some are available at Barton's own web site.

Also included is a limited edition poster and a hardcover art book featuring never-before-seen concept, development, and final artwork.

The PlayStation 3 version included the Variety map pack on the disc, and while the Xbox 360 Game of the Year edition initially included an insert in the packaging which could be redeemed on Xbox Live Marketplace to download the Variety map pack, later releases did not contain the inserts, and so were no different from the original release of the game.

As part of an exclusivity deal between Microsoft and Activision, multiplayer map packs for the Call of Duty franchise, beginning with Modern Warfare, were released first on Xbox 360.

GamePro notes that "the intense single-player campaign offers up an action packed experience that features a tremendously compelling narrative; there are moments in the game that will send chills down your spine.

[44] While IGN described the campaign as "still very linear" like that of its predecessors, "eschewing the concept of sandbox gameplay", it noted that this resulted in "a much richer, more focused experience" with "beautifully scripted set pieces.

"[69] Xbox World 360 stated "It's smoke and mirrors and a host of cheap tricks", commenting on the notion that the game did not revolutionize the genre.

[70] Pelit also remarked that "the structure of the single player game should ... have been updated" and that "barging from one invisible checkpoint to the next throughout the whole campaign just isn't good enough anymore.

[77] It fulfilled the prediction, with the Xbox 360 version became the best-selling video game in the United States from November 2007 to January 2008 according to the NPD Group.

[111][112] Modern Warfare has received critical acclaim for its campaign, characters, missions (particularly "All Ghillied Up"), and successfully breaking away from the series' World War II roots.

[101][106][103][108] Digital Trends summarized: "Modern Warfare's competitive multiplayer put a renewed emphasis on personal performance rather than winning individual matches, with players now carefully eyeing their kill-to-death ratio as they modified their weapons with custom sights and grips.