[Kalius]

Heart of Darkness (old and amazing game):
https://youtu.be/vC1pZwUQKhs?list=PLk1G6ljZMPs6tZ4LVWg7YjVjfuntbIXnW
 
Ori and the Blind forest (the whole OST is amazing):
https://youtu.be/s3J2WiVXAOo
 
Child of Light - Dark Creatures:
https://youtu.be/k5X0v7h5kWQ

Bastion:
https://youtu.be/hMBLXyVJy8Y

 

[hylas512]

There are many that I could list, but two spring to my mind instantly: most of the music in the Megami Tensei series composed by Shoji Meguro and the soundtrack to Eternal Darkness Sanity's Requiem by Steve Henifin.

 

[TazedMarquis]

My personal belief is that Final Fantasy VI has the greatest game soundtrack of all-time, and the ending track is an outstanding example as to why: ALL of the character themes are fantastic. The "Ending Theme," which encapulates all of them in a mammoth 21-minute-long medley, always brings a tear to my eye:
 
 
 
Some lesser-known works that I think are great are Lennie Moore's brilliant score to Outcast. This track is basically a full orchestral tone-poem (and I prefer the more evocative title from the original album, "World of Snow"):
 

 
From the LucasArts vault is Michael Land's darkly ethereal music for The Dig. Mostly ambient, but with massive, Wagnerian chords that extol the sublime vastness of the Universe. This is perhaps the most beautiful track:
 

 
To end on a more upbeat note, I love Chris Huelsbeck's Turrican music. This is his rearranged version of the opening of Turrican II, which sounds great on my cherry ZMF Omni:
 
 

 

[DrumsFillo]

Absolutely main theme from Halo

Everytime I heard it I hope to wake up in a spartan armor 

I made a tattoo about Halo, really love that saga

 

[ZJee]

Shadow of the colossus has an amazing soundtrack, the only issue is the only way i could find it is importing the cd here from japan.

 

[FunkyMonkey909]

I thought that Planescape: Torment had an amazing OST. 

 

[Myk28]

My favorite video game soundtrack
 
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[MikePio]