UNDERTALE has a great soundtrack: https://www.youtube.com/watch?v=B69GfSqEZEs&index=4&list=PLpJl5XaLHtLX-pDk4kctGxtF4nq6BIyjg
Also it is a great game, almost certainly my favourite. Not heavy on tough puzzles though, mostly on fun Touhou-like gameplay and really cute dialogue. Proxima may like?
Colorful Arty: seconded. I like the Cave Story soundtrack, and the game. (I'm a sucker for anything metroidvania...) I haven't heard the 3D version though, it's good!
Proxima: seconded! Touhou has fantastic music, and you have some excellent picks too! I know the piano for a couple of those, actually.
More good Touhou music, not on your playlist yet:
You might also like the soundtrack from Touhou 10.5 mostly remasterings or remixes of earlier songs: https://www.youtube.com/watch?v=tqAr1QkODIo&list=PL9758D4024B89B7BD&index=4
Also, Touhou 11 has the best and most varied soundtrack of any of them in my opinion, narrowly edging out Touhou 6. In particular, track 4 onward: https://www.youtube.com/watch?v=nWsoy4IPPJk&index=4&list=PL0F847C10EC47BD3B
Touhou 14 gets best menu music: https://www.youtube.com/watch?v=j1i0U6Vjn5Y
It's cute how they all work that melody in somewhere.