'Halo 3: ODST' game gallery

Fight fire with fire

Unlike “Horde,” though, the enemies are sent in randomly, so you’ll never know if you’ll be facing a particularly tough group or some pushovers. Like the similar Nazi Zombie mode from “Call of Duty: World at War,” it will be an endless battle, since the Covenant will keep sending enemies at you until you and your teammates have used up all your lives.