Sorry, Final Fantasy XIV players, it's not an in-game collab, or at least it's not yet. What is happening, in honor of the tenth anniversary of Undertale, is that Toby Fox is linking up with Squenix' Music and Merchandising division to release at least two albums and a line of apparel, with hints of other items to come.

The first album is a series of "chill" arrangements of music from Undertale, with twenty tracks in all. It's due to release at the end of January, with preorders available from the official Square Enix online storefronts in North America and Europe, and CDJapan in that country. Apparently at some point it will also be sold through Fangamer. It's not shaping up to be cheap, but then, would anyone really expect that?

The official site also announces a second album, full of piano arrangements by longtime Square Enix collaborator Yoko Shimomura, but with no tracklist or release date yet confirmed. Additionally, all other Undertale merchandise is marked as "Coming Soon" too, so don't expect to see it right away.

Source: Square Enix × Undertale Official Page