Eidos has confirmed that it plans to release Tomb Raider Anniversary on Xbox 360 as a series of downloadable episodes starting in September.
The content - Xbox Live's first ever serialisation of a full retail game - will be made available for owners of Tomb Raider Legend to purchase through Xbox Live Marketplace.
In September "Episodes 1 & 2" will be offered along with a free training mission ("Croft Manor"). The following two episodes will arrive "shortly afterwards".
Eidos then plans to release a full retail version of Tomb Raider Anniversary "later in the year" that will put it within reach of gamers who didn't buy Legend.
Tomb Raider Legend owners will have to pay 2400 Microsoft points (GBP 20.40 / EUR 27.91 / USD 29.99) for all four episodes.
Jane Cavanagh, chief executive of Eidos' parent company SCi, said the episodic approach was part of the publisher's strategy to grow its presence in online and digital distribution.
"Lara has always been at the forefront of technology and this world-first initiative with Microsoft really highlights that fact. Ultimately we also intend to make the title available at retail so that it reaches the maximum possible audience," Cavanagh said in a statement.
Tomb Raider Anniversary is out now on PlayStation 2 and PC.