Overview
(text is copypasta from MW3's CoD Wiki page)
Call of Duty: Modern Warfare 3 (stylized as Call of Duty: MW3, and also referred to as Modern Warfare 3 or MW3) is the sequel to Infinity Ward's Call of Duty: Modern Warfare 2. It was confirmed to be in pre-production on April 9, 2010 by Activision. IT came out November 8, 2011. Sledgehammer Games, originally planning to work on the canceled action/adventure Call of Duty, is working with Infinity Ward on the single-player aspect of the game while Raven Software is working on the multiplayer. Sledgehammer is aiming for a bug-free Call of Duty game and ratings above 95%. It has been revealed that Modern Warfare 3 will use the Modern Warfare 2 engine, for courtesy to Sledgehammer.
It will be available for PC, Xbox 360, PS3, and for DS under the name MW3 - Retaliation. Nothing is known about a Wii version. Special editions were announced, coming with some avatar clothing for 360 users and a special theme for PS3 players. It also comes with a Brandy Game Guide. A regular copy of MW3 is now available for pre-puchase though steam, although minimum specs have not yet been announced.
When a massive amount of leaked information was revealed by gaming news site Kotaku on May 13, 2011, Robert Bowling responded in a tweet stating: "A lot of hype & a lot of leaked info on #MW3, some still accurate, some not. To avoid spoiling the experience, I'd wait for the real reveal." Later that day, four teaser trailers for Modern Warfare 3 were released on Call of Duty's official YouTube channel. Each one revealed a different location: New York, London, Paris, and Germany.
The full reveal trailer was released on May 23, 2011. The trailer was leaked almost two hours before the scheduled air time, prompting Infinity Ward to officially release the reveal trailer earlier than planned. The reveal featured sequences from combat in all four of the previously confirmed locations.
Gamemodes
Campaign
The Campaign of MW3 has been comfirmed to take place in 4 main locations around the world, America (New York), England (London), Germany (Berlin), and France (Paris). There are also minor locations such as India, Africa, and the Czech Republic. Gameplay videos of 3 campaign missions have been released prior to the game's release, being of Black Tuesday, Hunter Killer, and Mind the Gap. The first two taking place in New York, the latter taking place in London.
Playable characters include Derek "Frost" Westbrook, a Staff Sargent fighting in New York and Germany; Yuri, essentially MW3's roach, traveling the world with Task Force 141; Marcus Burns, fighting in London; and Andrei Harkov, a guard for the Russian President Boris Vorshevsky.
Multiplayer
MW3's multiplayer was showcased at the Call of Duty XP convention. A youtube clip that has been taken down shows 32 player multiplayer on consoles and pc (unconfirmed.)
According to Activision's Eric Hirshberg the four principles of developing Call of Duty are: Epic realism (real world combat with "blockbuster" action); Adrenaline rush (want gamers to always have blood pumping and experiencing while knuckle moments); Easy to play, but hard to master (fun for new players while remaining fun to the hardcore gamer); 60 FPS (Using the processing power of gaming platforms to provide optimum performance)
Returning features include the private match customization of Black Ops, and playercards not unlike MW2. New features include 80 levels plus prestige, 28 killstreaks, 16 maps, and a new gamemode called Kill Confirmed, in which players have to collect dog tags taht hover over killed players bodies. If they do not collect it their team does not recieve points. There also weapon levels and a new way to unlock prestige bonuses, via a shop using prestige tokens as currency.
CoD Wiki's MW3 Multiplayer Page.
Special Ops
Special ops returns in MW3 with missions not unlike the MW2 version, and a new survival mode, which takes place on multiplayer maps. This survival mode is similar to the Zombies modes of the previous games, but now the enemies can shoot back. Known features include a weapon/equipment/air support shop, increasingly hard enemies (wave one is regular infantry, wave 10 has juggernauts, ect.) and new enemies (such as an attack dog with explosives.)
FAQ about Special Ops survival mode; conducted by Digitalspy, questioning Robert BowlingMedia