I never played any Virtual Boy games because I've been blind in my left eye since birth and I wouldn't be able to see the games very well. It's also why I'm a little bit apprehensive about all the new VR gaming technology coming out.
I guess it's the first sports game with Mario in the title, but don't forget that Mario was also in a couple of golf games and a racing game on the NES/Famicom.
I'm not a big Tennis game fan anyway. Most of the tennis games I played felt like just glorfied Pong clones. I first played a Mario Tennis game on the N64 at a friend's house, and it was kind of fun but not worth buying. I did get a Mario Tennis game on the Wii and didn't like it, so I'm not inclined to try the one on the Wii U either. I do like some of the other Mario sports games, though, like golf and baseball, etc.


