After thirty years of war with the Covenant, humanity finally found victory. The Master Chief, a Spartan super-soldier, and Cortana, an AI construct of unmatched technical sophistication, put an end to the Covenant, the Flood, and the threat of the Halo Array on a remote installation known as the Ark. Now, in the wake of the conflict, the Chief and Cortana drift through space aboard the remains of Forward Unto Dawn, slowly approaching a mysterious artificial world they will soon come to call Requiem.

Players can engage Halo 4 through a number of ways. In Campaign, players take the role of the Master Chief, the living legend of the Covenant War, a SPARTAN-II super-soldier wearing heavily modified GEN1 Mjolnir armor. Within War Games and Spartan Ops, players take the role of a highly specialized SPARTAN-IV super-soldier, deployed from UNSC Infinity and utilizing a state-of-the-art Mjolnir GEN2 armor system.