Kudos to Mhaddy, who pointed out a new but fairly basic Halo preview at Jack In Online Gaming. Most of you will likely be familiar with the information given in the article, but a particular paragraph stood out:
The totally unique mode is known as Ogre. For this, one player takes the role of the Ogre who will have a massive arsenal of weaponry and will be very, very hard. He will have several objectives to complete and it will be the job of everyone else to stop him whatever it takes. If someone succeeds in slaying the Ogre then he takes his place next time but if the Ogre completes his objectives, its controller can enjoy the power a second time around.
This description fits to a tee the game Ogre, by Steve Jackson, which places some doubt on it. In the event that Bungie does include this sort of game in Halo, one would expect that copyrights would necessitate a different name for it. Nevertheless, that doesn't rule out such a game being present...