Mario Kart 8 (abbreviated to MK8) is a kart-racing game exclusive to the Wii U. It is the eighth Mario Kart game in the series (eleventh overall if including the arcade games).It was released on May 29, 2014, in Japan, May 30, 2014, in North America and Europe and May 31, 2014, in Australia. .t is the eighth Mario Kart game in the series (eleventh overall if including the arcade games). It was released on May 29, 2014, in Japan, May 30, 2014, in North America and Europe and May 31, 2014, in Australia.