In fact it has been kept in "relative secrecy" as 343 was creating the latest Master Chief entry for "a couple of years." New Halo novels were unveiled as well.
Franchise development director Frank O'Connor of 343 Industries said Halo 4 had been in development for longer than people may have realised during the Halo Comic-Con 2011 panel. Also detailed were two new novels set for release.
Karen Traviss' Halo: Grasslands will be bridging events between Halo 3 and 4, and focuses on lesser known characters and groups like the Office of Naval Intelligence. Greg Bear's Halo: Cryptum explores the story of the Precursors and Forerunners in depth.
Halo 4 releases exclusively on Xbox 360 in holiday 2012.