I really could get in to plot and storyline but that isn't my way. But if your curious check out the article on Wikipedia
Now with that out of the way, lets get into the game itself. For that we turn to YouTube.
This is of the 2D version
Yes I am aware it's also a review of the game, but your also getting a fair review as I have not played the game.
For the record the 3D version
I had to post that so you could see the difference
Now if you like what you see head on over to the Official Site and get the download link. As for the 3D version you can get it from Nintendo's Eshop for $9.95 or a physical copy around $40. I am not sure what the 2D version cost from Nintendo.