Xbox users get more downloadable content via Live, including two new co-op maps, and a new versus map. Here are some details about the maps:

Versus mode: Polar Base

Somewhere in Antarctic ...

A military satellite has detected abnormal activity in this frozen and desolate place. A massive structure protected by an electrical fence and heavily guarded by Argus mercenaries has been constructed during last few months, leaving our forces with no idea of what secret lies beyond the walls.

Biological research? Nuclear? High Tech Weapons? Or worse ... You have to infiltrate the compound, hack communications and sabotage power generators in order to learn what is happening within.

But Beware, Argus corporation won't make it an easy mission.

Co-op mode: Introduction

The chemical attack on Grand Central Station (the final mission of Chaos Theory's Coop Story Mode) was prevented, but Colonel Kim fled. In fact the moving train was just a diversion to cover his escape. And the bad news isn't over: he may have more bio-weapons.

Co-op mode: Nuclear Plant

Echelon's investigation of the defused bio-bombs reveals a connection with a Nuclear Plant close to Yongbyon, North Korea. The CIA suspect it to be a cover for a secret Military Research program. Agents are sent there to discover who may have helped Kim, how many bombs he may have, and where he could attack next time.

Co-op mode: UN Headquarters

Intelligence gathered from the Nuclear Plant leads agents to infiltrate one of the world's most heavily guarded protected buildings: the UN Headquarters. With the mission set to be aborted if a general alarm is called (US agents must not be found in the UN building) - the agents must avoid all guards and civilians in a mission that ends with a deadly race against time.