I have no idea where I'd put Nine Inch Nails Ghost I - IV. It's kind of an assortment of instrumental genres that are relatively off key but amazingly fluent sounding. Trust me you should check it out!
Ghost III - 23 if your into heavier stuff and
Ghost IV - 34 if your into much lighter stuff.
I'd also think of other music like I monster - Cells, which is relaxing but thinking music, I dunno what genre to put that in.
I'd also think of the Binding of Issac soundtrack as something that doesn't really coincide with any genre
I've never heard of Norse Metal before, maybe I'll check it out see if it's any good