"Army of Two is a third person shooter video game developed by Electronic Arts, released on PlayStation 3 and Xbox 360, focusing on two mercenaries fighting through war, political turmoil, and a conspiracy from 1993 to 2009.
Focusing on cooperative strategies, Army of Two's main feature is the necessity to use coordinated teamwork to accomplish the game's goals. While the game is meant to be played with another human as a partner, a "Partner Artificial Intelligence" (PAI) is also included and programmed to follow the player's strategies. Dependence on a partner (whether human or PAI) is so pronounced that most objectives are impossible to complete without it.
The PS3 and Xbox 360 version of Army of Two is one of the first games for the console which will be region-locked for online play. EA claims that the region-locking is to prevent network lag caused by players from multiple regions, and to prevent the Asian region console owners from playing the US and European version of the game, as the Asian version has been censored to meet certain requirements (notably, the shooting of already dead bodies in the game).
A sequel, titled Army of Two: The 40th Day, was released for PlayStation 3, PlayStation Portable and Xbox 360 on January 12, 2010."
Source: Wikipedia, "Army_of_Two," available under the CC-BY-SA License.