From their Discord:

"Yesterday, gdkchan was contacted by Nintendo and offered an agreement to stop working on the project, remove the organization and all related assets he's in control of. While awaiting confirmation on whether he would take this agreement, the organization has been removed, so I think it's safe to say what the outcome is. Rather than leave you with only panic and speculation, I decided to write this short message to give some closure.

These words are my own. I don't want to speak for anyone else here, so just remember that while reading.

Thank you to everyone who has contributed code, documentation or issue reports to the project. Thank you all for following us throughout the development. I was able to learn a lot of really neat things about games that I love, enjoy them with renewed qualities and in unique circumstances, and I'm sure you all have experiences that are similarly special. I'm extending my own massive thanks to our moderation team, who have been here through some rough circumstances and always found ways to make light of it."

As of this post, the GitHub is closed and their downloads page is blank.