You can check out the teaser trailer here or below:
Can I be honest with you and mention that this trailer really irks me? I'm a huge fan of Halo fiction. Huge. I know how a lot of the tech in the franchise works, the science and specs behind it, as well as the personalities and motives of the various factions.
The honest truth is it makes no sense what-so-ever for John-117 to be wearing a cloak over his Mjolnir Mark VI armour; none what-so-ever. He's wearing one of the most advanced suits of armour known to man, and he's operated in hostile environments of all sorts before.
I truly hope the cloak was just for this teaser trailer, and seeing as how he's holding Cortana's data chip, I hope the focus of this game isn't to bring her back, seeing as how that would negate the emotional impact of her death in Halo 4 and further goes against the lore in terms of rampancy and the nature and creation of smart AI's.
But of course, the game's not out yet or even properly revealed in any detail, so we'll see.