An underrated game
You play as Elliot Salem or Tyson Rios who are employed as private military contractors. They are sent to all parts of the globe as they attempt to take out terrorist threats. Shortly in to the story, they realize that their boss is not exactly on the level, so in addition to hunting down all the standard bad guys in the middle east, Salem and Rios must bring the fight back to American soil to protect their names.
There is no shortage of real world weaponry in Army of Two. All of the weapons are unlocked right from the start, but you must purchase each gun in order to use it. You earn money by accomplishing various objectives (usually, kill someone or blow something up). The game is heavily focused on co-op gameplay, so you are never without your trusty partner. The co-op AI is better than average, and rarely does it do anything overly stupid. As an added bonus, your AI partner is not completely helpless either. You will often find yourself telling your partner to lay down suppressive fire while you flank. Often times, by beginning your flanking move, the enemy AI will attempt to run, and your partner will shoot him in the back. Nice.
While Army of Two is a bit on the short side, there is plenty of reason to go back through the game for extra achievements, or better yet with a friend using co-op split screen. If you haven't tried Army of Two yet, put it down on your list of games to try in the near future.