Much of the holiday 2015 video game lineup may still be in question, but one thing's for certain: 2015 marks the return of the Master Chief. Halo 5: Guardians is easily Microsoft's biggest exclusive this year, and the game is sure to move millions of Xbox One consoles upon release - that's just how popular Halo is.

That being said, when it comes to the game's story, fans don't know a whole lot about what's going on. Sure, Agent Locke is an established character at this point, but aside from an extremely cryptic trailer at E3 2013, no one knows why the Master Chief has suddenly gone AWOL. Microsoft's viral story campaign has dropped some teasers, and there's bound to be something story-related at E3 2015, but so far, 343 Industries has been quiet on what's going on with the Chief.

Surprisingly, the first big story-based reveal won't be taking place at E3 - in fact, it's already been released. Game Informer just announced that its July issue will be centered around Halo 5: Guardians, and some major story points have already been revealed...

While it's been known for quite some time that the Master Chief and Spartan Locke would be the game's two main playable characters, it looks like they won't be alone: each playable protagonist will be accompanied by a specialized team of soldiers. The Master Chief will fight alongside Blue Team, a group of three SPARTAN-II soldiers - while the team has yet to appear in a Halo video game, the Spartans have played a huge role in the series' expanded fiction. They'll also be playable in co-op, with each SPARTAN-II bringing their own loadout into battle.

Agent Locke will be battling alongside Fireteam Osiris, who consist of three SPARTAN-IV soldiers - one of whom is Buck, the commanding officer and main character of Halo 3: ODST. Buck's last appearance was a short cameo in Halo: Reach, though he hasn't been seen (chronologically speaking) since the end of ODST. Locke's Fireteam Osiris shares many of the same traits as Blue Team, with each member bringing their own tweaks to the franchise's core gameplay.

Better yet, it's not as if these teams will simply disappear if you decide to play solo: both Blue Team and Fireteam Osiris will take commands from the player, though the full extent of the tactical play have yet to be revealed...perhaps it's something Microsoft is holding onto until E3?

It's clear that 343 Industries is trying to push Halo 5: Guardians into uncharted territory: squad-based gameplay is something that the franchise has only ever dabbled in, and it'll be interesting to see just how far Microsoft pushes the concept. One way or another, one thing's for sure: the Master Chief won't be alone.

Halo 5: Guardians is set for a Oct. 23 release date. If you want to brush up on the series' lore, check out our Beginner's Guide to the story of Halo.

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