Nintendo has a good track record when it comes to keeping secrets, and in the case of The Legend of Zelda: Tears of the Kingdom, the Breath of the Wild sequel's announcement was one of the company's most confidential projects. In fact, the game's existence was so secret that many Nintendo employees only found out about it when it was teased during the E3 2019 Nintendo Direct livestream.
According to former Nintendo of America marketing and PR leads Kit Ellis and Krysta Yang, Tears of the Kingdom had a "higher level" of security than any other Nintendo project that they worked on, and they claimed that only a small handful of people at NoA knew about it.
https://youtu.be/eeyniV4efYM?t=3329Ellis, who was the director of social media marketing and original content at the time, said that he was trusted enough to be told about the sequel and that he had to work on it in secret, with his social team none the wiser. "I had a ton to do. There was this big communications team, like an E3 machine, cranking out materials, and obviously the main place for this was in the Nintendo Direct," Ellis said. It became clear, I have to do these different teams' jobs in secret, and when this happens, feed them this thing and tell them what to do with it."
Yang added that the official teaser was a big hit amongst the surprised Nintendo employees, with staff promptly celebrating the surprise reveal. A few years later, Tears of the Kingdom landed on Switch consoles and earned rave reviews across the world for how it expanded on Breath of the Wild and pushed its gameplay systems to new heights. Both games were also updated for the Switch 2 when it launched last year.
https://www.youtube.com/watch?v=3DRARZQexW4The franchise has had a constant presence on Nintendo hardware for several years now, with last year's Hyrule Warriors: Age of Imprisonment acting as a prequel to Tears of the Kingdom by detailing the events of Zelda's trip back in time. This year will see the launch of The Legend of Zelda: Ocarina of Time remake, and in the not-so-distant future, we're also getting a live-action Zelda movie and some new action figures.