Ooh…I have an entire playlist of my favorite OSTs. Long term, I’d have to say One-Winged Angel, specifically the remake. Also worth mentioning:
Dark Soul 3 main theme
Feel from Lies of P
Dependent Weakling from Nier, specifically this version: https://www.youtube.com/watch?v=ePXlfGufSjk&t=0
Mass Effect 3 - Leaving Earth
Scored by the great Clint Mansell, also check out The Fountain OST.
I think this might be at a sweet spot between being a well-known track and an unexpected top choice to answer this question - Kefka’s theme is iconic.
I’d still put FF6 as my top game soundtrack, but I’ll admit it’s easily possible that’s just a consequence of me not playing many games the past couple decades.
I’m partial to Terra’s theme, but yeah, that whole OST is amazing.
Jazz Jackrabbit 2 OST Carrotus
Dearly Beloved
The track during the balcony scene from the first Blade Runner point-n-click adventure game. Came out in 1997. It’s Vangelis’ iconic Blade Runner Blues
Just one?
Portal - Self Esteem Fund by Kelly Bailey
The volumes this song speaks through it’s atmosphere is incredible. The raw emotions and feelings of isolation are better conveyed through this song than words ever can in my opinion
My scrobbles say I’ve listened to this single song for more than 9 hours over the years… I have so many emotions bottled up in this song lol
Justin E Bell - All Gods from pillars of eternity
Metal gear solid- the best is yet to come
Probably nostalgia but guild wars 1 specially prophecies ( the first / base game ) had some absolute bangers for an mmorp and specially fitted for zones.
Expedition Society theme from Pokemon Super Mystery Dungeon. Has some commie marching song vibes.
Aquatic ambience - donkey kong country
Rusted apart from the unravel. That music is just too good
Laura Shigihara - Everything’s Alright from To The Moon.
That game made me weep like a baby, so even now, some ten years after playing it for the first time, that song still stirs up those feelings.
And for much the same reason, Daniel Lanois - That’s The Way It Is from Red Dead 2.
If you’ve played it long enough to hear that song, you understand.
Vigil from Mass Effect. I think it’s the song playing when you first get the galaxy map, and playing that game and seeing the world open up while hearing that song really put me in a great mood.