343 Industries is trying to outdo themselves with the Halo 5: Guardians campaign, billing it as the biggest in Halo history. Four-player co-op and a massive story spanning two different squads of Spartans only scratch the surface of what I saw during a eyes-on demo at E3 2015, and if what was presented to me during this demo is any indication Halo fans will have plenty to sink their teeth into come October.

Guardians features the largest cast of characters in Halo history, with many new and returning faces outside of the two Spartan fireteams. Dr. Catherine Halsey, the mother of the Spartan program, makes a return appearance, as does the Arbiter for the first time since Halo 3. The stars of the show are the two Spartan squads, known as Blue Team and Fireteam Osiris. Blue Team, headed by the Master Chief, is made up of Linda, Kelly, and Frederic, all soldiers that Master Chief trained with in the Spartan program. Fireteam Osiris is a newly formed squad led by Spartan Jameson Locke, consisting of Edward Buck (Nathan Fillion's character from ODST), Holly Tanaka (from the Dark Horse comic series), and Olympia Vale (star of the newly-released Halo: Hunters in the Dark novel).

343 Industries

These two teams showcase two completely different styles of teamwork, one forged by the bonds of long-standing friendship and camaraderie and the other forced onto the team members by honor and military code. The juxtaposition between the two is an interesting concept, and watching both sides of the story unfold should make for some gripping storylines. The two missions I saw during the demo, "Battle of Sunaion" as seen during the Xbox E3 conference and the "Blue Team" mission starring Chief and his crew, show some subtle differences in the way the two teams address one another and other small nuances you'll have fun spotting on your own. I'm interested to see how this all plays out.

Because there are two squads of four Spartans each, that means the entire campaign will feature co-op gameplay. In fact, the entire campaign has been designed with a co-op focus, as each enemy encounter, story beat, and level design has been crafted with the co-op format in mind. Players can drop in and out on the fly seamlessly via dedicated servers, although whoever is designated as the "host" must remain with the game or the session will be lost.

343 Industries

When a session has less than four players, the other Spartans will operate under what 343 is calling Fireteam AI, acting as closely to a human player as possible. They will take orders from the leader via the Fireteam Orders system -- which acts similarly to the orders system from Mass Effect 3 -- and will revive downed teammates without needing to be ordered to do so as a human player would do. This enhanced co-op focused AI will make it seem like there's always four human squadmates working together to conquer the campaign, even when there may be only one person in the session. However, despite the enhanced AI capabilities there is no split-screen couch co-op options available, so any team-based campaign missions will have to be done online. Also, all of the Fireteam Orders will be administered via button presses, as there will be no Kinect voice support within Halo 5: Guardians. Sorry, Kinect fans [Kinect... fans? - Ed.].

The ambitious campaign promises 343 Industries is making are impressive, but I can't help but take them with a grain of salt after the travesty that was Halo: The Master Chief Collection's launch. If everything comes out firing and the full co-op experience is functional from day one, then I have no reason to believe that Halo fans won't be enamored with the new campaign direction. Should connection issues once again plague the world of Halo, then I don't know what's going to happen. Let's hope 343 has it all figured out before this fall.

Halo 5: Guardians launches exclusively on Xbox One Oct.27.