What do you prefer? Or Do you have other idea?

TBH, I don't really think there's any 'must have game' anymore. There's far too much variety and quality in the games industry for that one killer app to really boost the Wii U's sales. Its kind of sad to say, but its true. Steam has the most extensive games library right at your fingertips, sony and microsoft have pretty robust physical and digital offerings as well. Sure the Wii U may have some amazing games with more in the pipes, but I just don't see anything being amazing enough to 'change its fate'.

The biggest potential system seller that Nintendo has in the works right now is Zelda, but lets look at Skyward swords sales for a moment. 3.88m lifetime with 101m Wii's sold. Meaning somewhere around 3.5% of Wii owners bought the last console Zelda title. Lets apply those numbers to the Wii U. 10m Wii U's sold(rounded up for simplicity) means 350,000 copies of Zelda U, but lets be super optimistic and say that 350,000 current Wii U owners will buy it, and another 1.15million people will buy a Wii U just for Zelda. Then lets take into consideration that Nintendo will probably sell about 3million Wii U's this year and add 1.15 for 4.15million. Assume a 6 year(generous) console generation and for some reason no drop in console sales for a steady 4.15m for the next 4 years and that puts the Wii U's lifetime sales at right around 26million units sold.

Sure some other games will come along that will move some extra units, but lets be honest here. The killer app just doesn't exist in the gaming world any more. Oh how I long for the days when Genesis did what Nintendont.

Nintendo And Square Enix Partners to Make Remake Final Fantasy VII (Exclusive)

Would fap

I wouldn't prefer it, but GTAVI WiiU exclusive would obviously be the one to do it.

why do i have the feeling i've seen this thread before

Mario 64 remake for me, but GTA VI exclusive would sell Wii Us, a lot of Wii Us.

The only games that would sell Wii Us are an exclusive GTA (how effing awesome would that be), or a fully fledged Pokemon RPG, with amiibo integration (I don't understand why they haven't done a proper console pokemon).

While a new IP seems the obvious choice, I'd get a real kick out of a WiiU exclusive FF VII remake.

Feel like the games most needed by the Wii U:

1) a 3rd person 3D mario game, like Mario 64. However dont just do a lazy port, make a new real game.
2) a "real" paper mario game for the wii U. This means old school RPG.
3) a Pokemon rpg for the Wii U, ports would be acceptable.

I dont think Nintendo should try to do what the others are doing, with their much much weaker consol.
A new GTA game would be a huge letdown when you notice its graphics will be really lacking compaired to whatever the Ps4/xbone has.

It should stick to what its good at, that it has under delivered on.

The FF7 one would make the internet explode.

Quite honestly, i want a pokemon RPG with connected elements. I would love for it to feel like playing through the pokemon series with your own trainer. I think that would be the game that could turn the Wii U around. A redesign to gowith it would be perfect.
Its a shame Nintendo doesnt push gamefreak to do it. They must be the only first party that is willing to not bringout the games that would sell their systems simply because the devs dont feel like doing that.