'Mass Effect' Xbox Live content launched

Microsoft has unveiled the first downloadable content for its best-selling Xbox 360 role-playing game Mass Effect.

The extra content, which is now available via Xbox Live Marketplace for 400 points, is entitled Bring Down the Sky and includes a new uncharted world introducing the Batarians, described as a 'notorious and feared alien race'.

As part of the downloadable pack, the plot follows a Batarian extremist group who have hijacked a mobile asteroid station in the Asgard system, setting it on a collision course with the nearby colony world of Terra Nova. According to Microsoft: "Only Commander Shepard can save the millions of innocent civilians before the asteroid completes its deadly descent."

The new pack, which Microsoft claims provides gamers with '90 minutes of heart-pounding action', is the first in a planned series of Xbox Live downloadable content.

Mass Effect, which sees players follow the adventures of Commander Shepard and the Normandy crew, has sold more than 1.6 million copies to date.