Halo: Chronicles is an episodic interactive story telling set in the Halo universe, as confirmed by Microsoft on April 24th, 2008. The game is to be a "new chapter" and a "new series" in the Halo story, is stated to feature a new way to play games, and is described by Jackson as the "filmiest game." It is set to be released in winter 2009.
Very little is known yet about the story line, plot, etc.
In the UK (United Kingdom) the Xbox 360 magazine Xbox World 360, it was speculated that the game will be more of an 'interactive movie' where some parts will be semi-playable, and certain decisions will lead to different outcomes that you then have to watch play out. It has also been stated that it will delve into Master Chief's back story.
It was confirmed by Shane Kim at GDC 07 that the project was an episodic title. According to Microsoft, Jackson is planning two episodic series for the Xbox 360. These games appear to be in a downloadable format. Microsoft went on to tell that the game is now in the development phase.
In an interview, Shane Kim elaborated on the nature of the episodic content of Halo: Chronicles, and on the relationship between Peter Jackson and Microsoft: