according to xbox magazine / gamespot...the chronicles of riddick isnt being released as backwards compat because its being retooled for the 360 as a new game ...almost . It will have all of the old stuff and a new title " Assault on Dark Athena ", but they want to put alot of new stuff in there and hopefully some multi player too . It will further the episode with more between him and Johns and some new blood .
Sierra formally announced Assault on Dark Athena--and answered some of the questions left hanging. The game will indeed "for the first time in the Riddick universe, take action in intense multi-player combat." Sierra clarified that said MP mode would be online-enabled. Both the 360 and PS3 editions of Dark Athena will be released later this year.
Sierra also revealed some plot details about the game. "The game introduces the ominous Merc-ship Dark Athena, which sits silent like a marauding spider, awaiting helpless prey in the dark reaches of the galaxy," the publisher said in a statement. "Players must face a large, bloodthirsty operation led by the dreaded Captain Revas and her slaves-turned-controllable combat drones, storm though death-defying events and fight fierce enemies in a battle of malice and gore."
...http://www.gamespot.com/xbox360/action/chroniclesofriddickassaultondarkathena/news.html?sid=6171213