Tomb Raider holds at No.2 for a fourth consecutive week.
Down 1.5% year-on-year, but a big improvement over large declines in January and February.
Trion Worlds' Defiance is new at No.3.
Available on all formats, plus launch exclusive DLC is now available for PS3 and PC.
The second biggest launch of 2013 and the biggest opening week for a BioShock title.