DialgaMarine on 15 February 2014
I would be inclined to say it's because the Gamecube already had it's own big Mario, Zelda, Smash, and few other popular ones like Luigi's Mansion to help it along. The only genuine big Wii-U exclusive to help is stand out is Pikmen 3 at the moment. I'd wait and see if bigger titles like MK8 and Smash help it sell more. If not, then the Wii-U may end up finishing as Nintendo's worst selling home console.
0331 Happiness is a belt-fed weapon
