Army of Two

Army of Two is a third-person shooter, centered upon 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.

Source: TheGamesDB