A top-down twin-stick shooter set in the Halo universe. Players control Spartan supersoldiers and battle a splinter faction of the alien Covenant across a campaign of missions, using series weapons and vehicles. Console versions add a cooperative survival mode in which two players hold out against waves of enemies.

Halo: Spartan Assault takes place in the 26th century, in the period between Halo 3 and Halo 4. A ceasefire has ended the long war between humanity and the alien Elites, but a breakaway Covenant faction refuses to honor it. Stationed on the planet Draetheus V, the Spartan soldiers Sarah Palmer and Edward Davis work to repel the invaders when the colony comes under attack. As the assault unfolds, the splinter faction turns its attention to an ancient weapon left behind by a long-vanished race, and the Spartans are drawn into a fight to stop it.