This screenshot caused massive consternation for awhile on several Halo forums due to a reflection on the visor which resembled a skull.

This shot of a Covenant Elite shows a form very similar to what appeared in the shipping game. Earlier shots had models that were much more grey than purple, and more closely resembled slightly less muscular versions of the Skaarj fighters from Epic's game, Unreal.

The hat of the marine on the right here earned him the name "Fishin' Bob".

From the announcement trailer. The Master Chief opens a weapons rack that is concealed in the hallway wall and selects an assault rifle.

Having opened the airlock door, the Master Chief prepares to fling himself into the Earth's upper atmosphere. From the announcement trailer.

From the announcement trailer. The Master Chief steps towards the camera, looking out through the observation window to the scene of Earth being "glassed" -- devastated by Covenant energy weapons.

From the announcement trailer. The Master Chief emerges from the door into The Spoke's fighter bay.

Another shot from the announcement trailer, showing off the new lighting effects of the Halo 2 engine as the Master Chief emerges into a darkened hallway with strong backlighting.

Whenever you see a sign that warns of danger if you push a button, you can bet you're supposed to push it. The Vidmaster's Oath, from Bungie's Marathon days, actually required players to "push all buttons". There's rarely a button in any of Bungie's games that you're not supposed to push.