Bungie mystery project: Halo prequel, Forerunner, or next-gen Marathon?

[Microsoft News]

Halo-heads had a steaming cauldron of piping-hot speculation poured into their laps this week, courtesy of a trifecta of wild rumors.

http://www.gamespot.com/news/show_blog_entry.php?topic_id=24847371&part=rss&tag=gs_xbox&subj=6154857