Ambient began as a kind of avant-garde approach to making electronic music. It then became synonymous with new age and easy listening. But the essence of what Ambient is, is that it's creating soundscapes, and they don't have backbeats. It's a wonderful exploration of sound. It can be relaxing, scary, boring, enticing, and tends to pay off the more you pay attention.
Ambient is very nebulous and can mean a great deal of things. There's a whole wing of electronic music similar to and inspired by ambient, but isn't technically ambient. This tends to be called chillout, or downtempo, or ambient versions of dance genres. Ambient House, Ambient Techno, Psybient, etc. They won't find themselves on this list with maybe only a couple exceptions. I love chillout, I just don't listen to it and ambient in the same way.
There's several niches in the world of ambient that have had lasting impacts in the music world. The big 3 ambient subgenres are Space, Dark, and Tribal. Space Ambient is a dead ringer, shit that sounds science fiction and goes weewo. Dark Ambient is a little bit more involved, and takes a special touch to take what should be relaxing and make it more akin to a pair of gloves violently squeezing you by the neck until you pass out. That last trend, tribal. A meaningless term. Tribal is a meaningless term that has a coded racist meaning to it in most contexts. But more innocently, it means ambient with world music elements. Which, world music ambient is good.
Alias Conrad Coldwood - OFF OST
That french indie game everyone was horny for about a decade ago. It had a pretty great soundtrack.
Cabaret Voltaire - The Conversation
Not the sendoff hardcore fans may have wanted, but hardcore fans tend to not appreciate what's in front of them.
Andreish Gandrabur - Pathologic OST
Probably the most effective ambient game OST, but you should listen to it anyways even if you have no interest in Pathologic for how it creates an alien atmosphere while also being deeply rooted to the earth.
Global Communication - 76:14
Nine Inch Nails - Ghosts
Back in the 90's this guy wrote a song about sex. how crazy is that huh? Anyways now he makes the facebook OST. At the time this album came out, nobody really liked it, because it had no songs about how Trents girlfriend who is a metaphor for drugs is a big old mean bitch. It's always good when bands outgrow their fans.
Oneohtrix Point Never - Zones Without People
Imagine turning this album into a whole electronic genre. Ridiculous.
Oneohtrix Point Never - Russian Mind
Oneohtrix Point Never - Replica
The Orb - The Orb's Adventure Beyond the Ultraworld
I'm not british fyi
Steve Roach - Structures From Silence
Mikko Tarmia - Penumbra Sountrack
This is the dark ambient album that taught me how to love dark ambient, and it came from the horror-adventure that taught me to love horror-adventures. It does every single thing right, to create a claustrophobic, doom tinged, depressive picture in an abandoned mining facility in the arctic, better left alone.
Mikko Tarmia - Amnesia: The Dark Descent
More of a goth ambient / neoclassical / ethereal kind of release to fit with the theming of the game, but it's built on top of the best songwriting from the Penumbra soundtrack.
Mikko Tarmia - SOMA
A bit of a 180, going from modern times, to the romantic/victorian era, all the way to a subnautical future setting.. It's pulled off really well. Maybe I'm just a stan for him and for Frictional Games. I just hope they always have this guy making their soundtracks, I'll be happy. (if Frictional Games is reading this uh.. you hiring? check out my art page)
Underworld - I'm a Big Sister, And I'm A Girl, And I'm A Princess, And This Is My Horse
good for her
Various Artists - Homestuck Vol. 8
At least listen to Cascade
Akira Yamaoka - Silent Hill
Much more dark and industrial than Silent Hill 2
Akira Yamaoka - Silent Hill 2
The platonic ideal of an ambient sountrack for a horror game.