Starting in September, Eidos will release Tomb Raider: Anniversary in serialised form over Xbox Live Marketplace. Episodes 1&2 will be offered first, along with a free training level (Croft Manor). Episodes 3&4 are scheduled for release "shortly afterwards".
In order to access the Tomb Raider: Anniversary episodic content, players will require a Tomb Raider: Legend game disc. The entire package will cost 2400 Microsoft Points, which in real money comes to around £20.
If you don't own Legend or you're simply not into downloadable games then Eidos is also planning to release a full retail version later this year.
Tomb Raider: Anniversary is out now for PlayStation 2 and PC, with Wii and PSP versions also in the pipeline. For more on the game head over to Pro-G's Tomb Raider: Anniversary review.