http://www.ign.com/articles/2012/11/...ept-art-leaked
Leaked materials provided to IGN by a reader have revealed story details and concept art from Destiny, Bungie’s follow-up to the Halo franchise. Bungie has confirmed to IGN that the document was prepared by an advertising agency and represents an outside look at Destiny’s plot, key values and more.

According to the document, “Our story begins seven hundred years from now in the Last City on Earth, in a Solar System littered with the ruins of man’s Golden Age. A massive, mysterious alien ship hangs overhead like a second Moon. No one knows where it came from or what it’s here for, but only that it’s our protector. Meanwhile, strange, alien monsters creep in from the edge of the universe, determined to take Earth and the Last City. We are young ‘knights’ tasked with defending the remains of humanity, discovering the source of these monsters and – eventually – overcoming it.” Elsewhere in the document, the massive alien ship is referred to as “the Traveler.”
At the link you can see the concept art for the game. For those that don't know Bungie is the creator of Halo and left Microsoft to work on games across all platforms. However Microsoft has a 12 month exclusive window on the game. I guess it was part oft heir agreement when Bungie decided to split. It looks very interesting.