Nintendo had worked with Koei-Tecmo before on a major project, and that was the successful Hyrule Warriors for the Wii U and 3DS. It was so successful, they wanted to pitch more projects to Nintendo and it seems one of those pitches was approved.
YouTuber OBE1plays first claimed that Koei Tecmo is developing a new Nintendo-themed Warriors game for Switch. Apparently, the project is not a retread of Zelda, nor is it based on Star Fox. Laura Kate Dale, who has been posting Switch rumors over the past few months (many of which have proven accurate thus far), wrote last month that Koei Tecmo pitched a Star Fox Warriors title at some point, but Nintendo turned it down.
Following OBE1plays’ report, Dale wrote on Twitter that she’s heard similar things about Koei Tecmo’s Switch game. She as well says it isn’t related to Zelda or Star Fox.
A YouTuber clamed that Koei-Tecmo is making a new Nintendo themed warriors game and Laura Kate Dale said she heard similar things in the past. Considering her track record, it would seem that another Hyrule Warriors style game is in production for the Nintendo Switch. The most interesting thing, is that nether Zelda nor Star Fox would be that game, considering this rumor states it’s not based on either franchise.
When Hyrule Warriors was finished, the studio stated they would like to make a Matsu style Mario title. Even then, other franchises like Kirby, Fire Emblem and Metroid could work well under that style of game. We will hopefully hear word on this rumor during the Switch Event on the 12th but keep in mind the following; rumors are not official announcements so please do not take them as such, wait for an official comment/statement from Nintendo or Koei-Tecmo for confirmation on any information related to this rumor.
Source: Nintendo Everything