Whenever this music starts playing I get on edge, and if I hear a Space Pirate moving behind me, I definitely get spine chills
And then there's Metroid Prime's Second Phase
The Nancy Drew PC games have some really cool and eerie music (way too many to shout out, but here's a few)
I also took the time to make some suites out of the music in the files from Outlast 1 & 2, but I haven't uploaded them anywhere so I can't share those. They're some of the most spine-chilling music in my collection though for sure!