Despite the severe blow dealt to the Enclave at Project Purity, their forces continue to linger and threaten the populace of Capital Wasteland. It now falls on to players to work with the Brotherhood of Steel to hunt down and finish the Enclave. Return to the Capital Wastelands, where the remains of a dead civilization blend with the skeletons of the dead, both recent and ancient.

With an increased level cap, dangerous new foes, and devastating new weapons like the Tesla Cannon, Broken Steel continues the story of Fallout 3 to its true conclusion, taking players further into the ruins of a former civilization, and the world beyond the apocalypse.