http://www.gameinformer.com/News/Sto...1318.40671.htm
Swimming mode enabled.
- A 'Stealthy' Oil pipeline Scuba Mission will be included in campaign mode.
- A level will definetly be based in Rio De Janeiro.
- Siberian Level will feature in campaign mode.
- Vehicles (e.g. Trucks, Tanks etc.) will be introduced into the Modern Era.
- A 'Helicopter Based' Level will be featured.
- An Oil Tanker level will also be featured.
- Ken Lally (Wesker from Resident Evil 5) will be voice acting. Most likely as a Russian villain.
More details and a new gameplay trailer will be revealed on May 24th
-No coop (for story)
-Special Forces mode, several missions in the spirit of Mile High Club (may have coop)
-More open ended gameplay
-No infinitely respawning enemies
Soap is in the game as a "grizzled vet" NPC.
Single player enemies will have "customized" weapons similar to the multiplayer component of COD4.
The ice mission shown to GI demonstrated the game's open-ended approach to combat, showing how stealth can be implemented if the player chooses.
While the gameplay is open-ended, the story is "on-rails".
Infinity Ward realizes that the "invisible line" where enemies will stop coming in COD4 wasn't great, so they're trying hard to eliminate that. Also, they are lengthening the single player past the 6-10 hour mark of COD4.
"Special Forces Mode" is a major part of MW2, a series of missions in the spirit of the Mile High Club from COD4. It will also have co-op in this mode. Gears-style bleed-out-and-partner-revive will be used.
Co-op apparently won't exist in Story Mode.
Riot shields will be implemented in the game.
Zakhaev's former associate, Makarov, is the "new face of global terrorism."
Snowmobiles are used as a form of escape in the demonstration. Unclear whether or not the player will drive, shoot, or both.
Players will alternate using the two triggers to climb ice-walls.
Movable turrets will be used in SF mode and Single Player, no official word on online use.
IW wants to implement an accomplishment system to online, as they want to make their players famous.
Online mode will use a "Live-Patching" system, where IW can manipulate spawn logic or certain parts of a multiplayer map without doing a full-blown patch.
Another demoed area shows an enormous desert setting where Task Force 141 drops into a wasteland and must navigate a "lengthy trek" to a fully-rendered valley with scattered caves, reminiscent of Iron Man.
IW is focusing on details for the COD4 sequel, citing iced-up tire treads in the Russian level.
The game will run in 60fps (duh).
Modern Warfare 2
It makes sense. 
Linear Mode
