First and foremost, there's nary a whiff of gameplay to be seen here. It's a simple slice of cinematic goodness, serving mainly to remind us of the wallet-plundering power of Halo.
It's a series with such cachet (and when you have enough cachet to warrant the use of terms like 'cachet' and/or other pompous prick-ery, you've got a whole lot of cachet right there) that we were treated to the special scene above, and E3-attendee excitement ensued.
An unknown dude dicks about in a cloak in a sandstorm, only for a spacecraft's ‘tailwind' to blow back his hood and reveal Master Chief's iconic helmet --not in a ‘penis' sense, that's not where they were going with this at all-- in dramatic fashion. As a glorious chorus plays in the background, like he was some sort of messiah or the pizza guy or someone else of divine importance.