3. Mario Kart 7 (2011) - 11.85 Million
The thing with looking at game formulas is you happen across those inimitably perfect concoctions of code that can never be replicated, only iterated on. Mario Kart - or kart racing in general - is something that launched pretty much fully-formed, and although titles like Crash Team Racing, Diddy Kong Racing and Sonic All-Stars Racing would come along in the future, for many, it's the original that's the best (even though I'll totally fly the flag for Crash). For Mario Kart 7, it was the plumpy plumber's first foray onto the 3DS, and that meant changing things up for Nintendo's flagship handheld. Graphics were noticeably improved regular DS version alongside the customsary new courses and karts, but best of all were new aerial sections where your kart sprouted a hang glider add-on, or underwater chunks of the course where you'd suddenly be surrounded by copious amounts of bubbles and fish. It opened up the very idea of what Mario Kart 'was', and led to MK 8 featuring upside-down courses and even crazier designs across the board.