'Mario Kart 8' has been released since May 30, and the sales have been staggering ever since. However, the long-awaited Mario racing game created a shift in favor of the Wii U console in the U.K

The game was only second to 'Watch Dogs', an action-adventure game, that launched on May 27 for PS3, PS4, Xbox 360, Xbox One and PC.

"While there is no contest for top spot, Wii U exclusive 'Mario Kart 8' races comfortably into second place. The much-loved series makes an impressive debut becoming the bestselling week 1 for any Wii U title since launch and the second-best in the Mario Kart series ever," said GFK Chart-Track, a software sale monitoring company.

"'Mario Kart 8,' like 'Watch Dogs', also launches an official hardware bundle this week boosting the sales of Wii U hardware by a whopping 666 percent, of which 82 percent are the Mario Kart 8 Bundle," GFK added.

The game has 32 courses with two separate versions of the Rainbow Road track. The developers said the had to work intensively to improve the franchise.

"Game balance is a really important element of Mario Kart that we look very closely at and place a lot of value on," Hideki Konno told Gamespot.

"From the time we start working on development, thousands of times, maybe even tens of thousands of times, we adjust that balance when we're playing. At the end, we come up with what we hope and feel is a really good balance. It's our strong hope that folks would want to play with the items as we have balanced them," he added.

The game was unveiled during the E3 event last year. It is still on demand at present and it is believed to be a hero for Wii U's sales. However, Nintendo has not yet revealed the exact figures of the overall sales of 'Mario Kart 8'.