One of the biggest changes to the Halo series coming with Halo 4 is the introduction of Spartan Ops, which takes the classic Halo co-op gameplay and spins it off into its own adventure. Spartan Ops' episodic additions will tell the story of the UNSC Infinity as it intersects with the events of Halo 4 and beyond.
Check out the new trailer below for a look at one of the Spartan Ops missions in action. It looks an awful lot like Halo co-op, but when that includes all of the new enemies, visual upgrades, and other bonuses that Halo 4 is bringing to the franchise, that's not a bad thing.