Eidos announced that Tomb Raider: Underworld will get downloadable chapters adding six hours of additional gameplay to the game. The catch is that despite the game coming to multiple consoles including the Xbox, Wii, and PS3, the downloadable chapters are Xbox exclusives.

The chapters will include Tomb Raider: Underworld - Beneath the Ashes and Tomb Raider: Underworld - Laura's Shadow. The Ashes chapter takes place after Underworld is finished and adds a new environment to explore with more enemies and secrets. Lara's Shadow adds a new kind of playable character. Beneath the Ashes will be available this Christmas and Shadow will follow in 2009. There is no word on pricing for the chapters.

“We’re thrilled that Xbox owners will be able to extend their Lara Croft adventures with exclusive Tomb Raider: Underworld episodes,” said George Peckham, General Manager of Global Third Party Publishing for Microsoft’s Interactive Entertainment Business. “We look forward to continue working closely with our great publishing partners to deliver the most robust gaming experiences, only on Xbox 360.”

Via Tomb Raider