Marty O'Donnell.

"We're creating something completely new, and that's a scary place, but if it's not scary, then it isn't going to be good."

-- Martin O'Donnell

This scene looks like it belongs to Earth's moon, perhaps overlooking the Hellmouth location pictured in other concept art images.

The color scheme makes this scene seem reminiscent of Covenant environments from Halo, but the structural elements in the distance seem human in origin, while those closer to the camera have that vaguely organic look Bungie has assigned to alien technology, most notably the Pfhor and the Covenant.

No action here, but our Guardian buddies sure do look good walking up some stairs.

The group of Guardians continue to advance towards the portal-like object.

As the players pass, the low pod-like object on the ground to the left glows with a golden sheen, perhaps indicating that it is a territorial marker, or perhaps something analogous to a Halo weapon drop pod.

Looking over the barrel of a futuristic-looking gun-- now it seems that we're looking at in-game footage or something close to it.

The artifact in the distance glowing blue may be some kind of transportation portal used for fast travel while on planets-- sort of like a World Knot from Myth.

The best thing about Bungie is, even though you know you have these crazy ideas, you know that they're going to get funnelled into a game that's fun.

A robot of some kind patrols the tower area. If the Guardians are all human, and the only other robots mentioned so far are Vex, these may represent another force, perhaps direct agents of the Traveler who act to keep peace in safe zones, much like town guards in an MMORPG, or Concord in Eve Online.

Another scene that appears to be in-engine, if not in-game.

This is the first shot in the ViDoc, aside from perhaps some of the spacecraft scenes, that look more like in-game footage than just concept art, or renders of game assets against a blank background.

Presumably this is the tower area overlooking the city where Guardian characters will congregate.

We're building something alive. It has a nature that we don't totally control. Things are going to happen that we don't plan, and that's amazing.