The first downloadable content extension for Call of Duty: Black Ops goes on sale today around the world, exclusively for XBOX 360. The offering is called “First Strike” and it has five new levels in it and four brand new multi-player maps and a zombie level called “Ascension.”

The game has been a worldwide smash hit. Within 24 hours of going on sale, Call of Duty:Black Ops had sold more than 7-million copies, 5.6-million in the U.S. and 1.4-million in the U.K., breaking the record set by its predecessor Modern Warfare 2 by some 2.5 million copies. Wikipedia reports that “by December 22, worldwide sales of Black Ops exceeded $1 billion”.

Now the franchise has been extended with exclusive downloadable content (DLC) that will keep the game alive and relevant for avid fans.

Marketing and PR company Megarom states that “we have done an initial test for the local South African XBOX360 accounts, all is looking good and ready for consumers who wish to download the additional content.”

The exclusive content will be made available from 1 February on XBOX360 only, before being extended to other platforms later in the year.

The DLC is available for 1200 Microsoft Points.