6. Call Of Duty: Black Ops (2010, PS3 & 360) - 27.2 Million
Back to Call of Duty - and the last COD on this list - as Treyarch returned, licking their wounds after the fairly lukewarmly-received World at War, ready for round two. Obviously the multiplayer was as stellar as always - introducing One in the Chamber mode that saw you have one round each, killing to gain ammo - but the best part came with some of the best written story moments since you shot Zakhaev in the original Modern Warfare. Without spoiling just incase there are those out there yet to experience it (and if that's the case, pick up a copy, I guarantee it'll be going for a pittance these days), Black Ops told a far more intense and character-focussed tale that opened with you being interrogated for information you may or may not know. From there it's a hearty mix of LOST-style number-pondering and player agency mixing with the game itself (you can 'break free' of the title screen if you try hard enough), delivering what is for my money, the best Call of Duty since Modern Warfare 2.