Nintendo just launched a peak behind the development of Legend of Zelda Breath of the Wild, started the idea in earliest of January 2013 and plan to release that in 2017. But there original goal was to release a little sooner than the release date. Even some of their promotional materials was dated 2015, then moves again to 2016 and ultimately chose the March 3, 2017 as the release date to let them improve the game and make it as interesting as possible.
Thinking about the game style of the Zelda series from the very start of development. There process is to think different mechanics and try to distinguish between the unchanging universal traits of the Zelda franchise. The things had simply become conventions of the series, some things were decided right from the start, but other decisions came later. Then settled their direction and broad concept first, and then the entire Zelda team got together and considered what to change and what to leave unchanged.
See the full video below.