Fun idea and great for kids but how much playtime would you realistically get out of this? Seems like it would be boring to see repeating scenes of your own home after a while.
You raise a good point, but it should be possible to remedy that if they wanted to. A possible solution could be that a course is generated based on the available track space in your home while looking like a typical mario kart course, no? When you think of the recent advances for Flight Simulator for example, something like that should be possible at least.
It's just Nintendo's ad but I thought the online/offline game interplay was interesting enough to warrant a submission.