It's a collection of piano sheet music of most of the tracks from Hollow Knight's soundtrack. The arrangements are really good and accurate to the source material. And there are nice illustrations at the beginning of each piece.
I used to play for like 10+ years but stopped a couple of years ago. I intended to use this as a motivator to get back to playing the piano. Didn't work too well yet, but I'll get there soon, I hope. :D
It's a beautiful soundtrack. Christopher Larkin deserves all the same praise as the greats of the past.