I have several suggestions.
Paper Mario: The Thousand Year Door
This soundtrack is pretty lighthearted for the most part. Not sure if it'll be your cup of tea.
https://www.youtube.com/watch?v=uWwHUKUNFyU
The Binding of Isaac: Rebirth
This soundtrack is all about metal and darkness. It's unnerving and intense.
(Rebirth got a DLC that adds more music along with its content. Here's the music added in the DLC.)
Undertale
You're going to get suggestions for Undertale. The soundtrack's good.
Mother 3
LISA
This is a strange one. The soundtrack is varied. It can be wacky and upbeat, intense, or really unnerving.
https://widdly2diddly.bandcamp.com/releases
It also has a DLC that expands on the story a bit. I'll give the soundtrack to that.