Infinity Ward calls this "the best thing we've ever done" (has a developer ever said, "This is the crappiest thing we've ever done") and they've been working on it since before CoD2 was completed, which is why Treyarch did all the work on CoD3. They've been busy doing research on modern weapons (they have a military advisor on staff), uniforms, settings, vehicles, and put everything together in a storyline they've developed.
They also made a conscious decision to avoid the war in Iraq and work on a unique story of their own. In the game, a Russian ultra-nationalist named Zakiev is trying to bring Russia back to its former glory days, but he's using a poor set of social skills in doing so by using massacre, assassination, and so on to secure his position. He's also working with some other nasty baddies to get things done, including Al Asad, a bad guy from ... the Middle East, surprise!
You'll confront this threat throughout the game as you play either a Force Recon or British S.A.S. soldier, although they promise "cameo" roles that will let you play different types of soldiers for a single level. We saw this demonstrated in a fairly creepy (yet amazing) level where you played the gunner in an AC-130 gunship. If you've seen the videos on YouTube showing thermal images of enemy combatants on the ground as they get taken out, this level is built to look just like one of those videos. It's incredibly well-done, but it's also somewhat disturbing.
The game also features no campaign system like the past CoD titles. Instead the game "unfolds like an action novel of a television series." To that end, they've developed the look and feel of the game to be hyper-realistic, and spent a lot of time on things like particle effects, clouds, changing depth of field, water, real-time lighting, and very detailed matte painting backgrounds. They promise that the "greasy and plastic looking" characters are gone, replaced by models that look more human. The soldiers will even sweat in the desert levels. The four soldier models they showed us were extremely detailed, down to the stitching on their clothing, and you could even read the time on their watches. Pretty cool stuff.
The multiplayer also got a complete overhaul, and they mentioned that the reason why the CoD2 multiplayer was so rough initially was because Microsoft changed the firmware at launch, which ended up breaking their multiplayer code. Oops. The new multiplayer is entirely class-based, and you outfit your soldier not only with primary and secondary weapons, but also up to three "Perks" and special abilities. These are things like extra gear, a GPS jammer, more damage, dead silence (stealth), and a really cool one called "last stand." Last stand lets you push a button when mortally wounded, which pulls out your pistol as you lay bleeding out on the ground. You can then fire wildly at your attacker(s) until your finally drop dead. Good for revenge killing or telling your teammates where the bad dudes are.
There's also a experience bar in the multiplayer, and as you get better you can level up your character, get promotions, and so on. There are no vehicles in the multiplayer, it's all infantry based, and will include Deathmatch, Free For All, Capture the Flag, Search and Destroy, and other gametypes. They also incorporated some of the more popular mods for multiplayer, so there's no crosshair mode, no HUD, and no regenerating health, so basically "be careful out there." During the match we watched you could see leveling up actively happening during a match, witness players (with powerful enough weapons) shooting through walls, and in some cases ceilings to take out an enemy above them. You can also call in things like airstrikes or satellite recon from time to time, depending on your outfit. It's also party-based, meaning your friends can jump into a match at any time.
The game was shown to us (in an extremely nice theater room at Infinity Ward) on a big screen, and on an Xbox 360, which they also ran the trailers and demo videos on. Some of the developers we spoke with said the PS3 version will look basically the same as the 360, and that there is no Wii version being planned (saw-Wii!). They're also planning on issuing a press release soon for the "special voice talent" and "well-known television writers" they were able to get for the game. Well, David Chase isn't working on The Sopranos anymore, so here's hoping.