I'm pretty biased on this one but for me it's definitely Mario Kart 8. Splatoon, however, would be a close second.

Didn't even take me a half a second to come up with the answer Mario Kart 8. It's probably the only Nintendo game this generation where I have basically no meaningful qualms. Frankly just thinking about it makes me want to play it.

What exactly is good about Splatoon? From what I played, it is incredibly small and repetetive.

If we are including the 3DS, Fire Emblem Awakening and Kid Icarus: Uprising NEED to be toward (if not out right on) the top of the list.

It actually has variety, but like most multiplayer games Splatoon is only good if you get into it and explore its systems/mechanics.

When it comes to Nintendo games this gen, I gotta give the nod to Fire Emblem Awakening as the best I've played. I've never been so invested in such a strategy game. It's accessibility is great for a newbie of strategy RPGs like me. Smash Bros for Wii U, Xenoblade X, Pokemon Y, and Splatoon are also right up there this gem for me.

Xenoblade Chronicles X for me. Hopefully Zelda Wii U takes it's place later this year though.

Fire Emblem: Fates by a loooooooong way. There's so much content in the game. Three separate storylines, all different from each other with different maps and mechanics. The huge total amount of characters (really a regular amount of characters of an FE game if you only play one side of the story) doesn't diminish any of the characters' personalities, they're all very well developed. It's an incredible package.

Awakening is 2nd for me, followed then by Bayonetta 2.

"Small and repetitive" is one way of putting it, "fun and fast-paced" is another. The idea behind Splatoon and many of the greatest online multiplayer games is that you take a really simple set of mechanics, and perfect them. Then it's down to the player to find a way within those mechanics that they like to play. There's depth to be found if you want, but the game never forces you to bother with that - it can also just be simple fun. I liken the game to the excellent Rocket League in terms of how it creates short-form morish online multiplayer in this way. I imagine it's not everyone's cup of tea - X it ain't, that's for sure.

I wouldn't label it as fun after about an hour or so of play.