Defense Grid: Your Monster

GLaDOS, the menacing AI from Valve's awesome Portal franchise, guest stars in this 8-level story expansion of the award-winning tower defense game Defense Grid. Players will battle not only alien hordes, but the deviousness of GLaDOS as she tests the player’s skills and changes all of the rules. In addition to the 8 new maps, Defense Grid: You Monster features 35 challenge missions, many new achievements and over 15 hours of additional game play.