Star Fox Zero was the only high-profile first-party exclusive announced for Wii U for the upcoming spring period (Q2 2016). However, despite Nintendo reconfirming their launch plans for April via an official press release just last month, the truth is no new material has been shown in recent weeks and now there are some indicators suggesting that the fox-fighting starship shooter might well end up being delayed further (and this would actually be its second delay). The reason? The insistence on implementing motion controls might have caused some QA problems.
This is only a rumour at the moment, but comes from the usually reliable Liam Robertson, who claims on Twitter that the Quality Assurance team at Nintendo of Europe "is going through a bit of a nightmare to get it ready", and that they have two weeks left in order to green-light the game. Apparently Miyamoto & his team's persistence on trying a never-before-seen GamePad plus TV gameplay scheme could have led them to difficulties with the controls. Now it's really a matter of Nintendo confirming, denying or showing how the game plays. We await more news with interest.