For me, it would be the Heroes of Might and Magic II soundtrack. It is the soundtrack I grew up with more than 3's and includes several famous tracks like the Grass Theme.

My favourite soundtrack would have to be the original Doom 1 soundtrack, every track suited the game so well and it's one of the few I have listened to outside of the game. (With an honourable mention to command & conquer)

Definitely Morrowind. Morrowind itself brings forth an immersive environment unlike any other game. Layered with the music composed by Jeremy Soule the player is bought into a world that is unique and memorable, even 20 years after it was released.

The soundtrack from original Starcraft. It completes the immersive environment. I can still hear the music in my mind years later and it never gets old.

I'll put it simple and right to the point:
Heroes of Might Magic 3 - because we used/played it when playing pen&paper games like Dračí Doupě 1.5 and AD&D (we played it back in thoes times) too.
I still remember Rampart music for travel and Tower music when visiting big cities. Battle music during fight...

Why else would I apply to this competition? I still play pen&papers and returning to good old memories with music provided by Good Old Games seems to be good and old fashion.

I'd have to go with Heroes of Might & Magic II because it captures my entire childhood. The battle music from the vanilla game is just perfect and the operatic vocals on the town screens were a really unique touch. The Necromancer theme still creeps me out every time!

Honourable mentions to Halo: Combat Evolved, TES3: Morrowind and The Sims 2 :)

Oh, definitely Vergil's theme - Bury the Light, from DMC5, he just such an iconic character and the song is suitably intense and energetic. The lyrics are also quite sad when you listen to them closely, which is an added bonus because it, again, just fits Vergil's character so well :D

Castlevania Symphony of the Night. Best game ost ever.

I was one of the few kids around that had a Panasonic 3DO as a kid. One of the games on that system was a first person shooter named "Quarantine". The game was very "off the wall" and the music fit it perfectly! The soundtrack was from a bunch of Aussie alternative bands (I think the game was made in 1995, so that fits) and so you only got to know their music through the game since music streaming wasn't a thing at that point. Very good memories from that time and this game. You should check it out!

Xenoblade Chronicles
You are dealing with regular enemies, when suddenly "You will know our names" starts to play. You just know that shit's gonna hit the fan, a unique monster joined the fight.

There are so many…

I could say Super Mario, the 8-bit game, because it was just epic, plus I actually heard it at “gaming in concert” which was a concert with a symphony orchestra playing music from games.

Or World of Warcraft, because I’ve spent SO many hours in that game, and made a “reading”-playlist with that.

Or Diablo 2, mostly the 2nd act, Lut Gholein, because that’s also just one of the most recognizable pieces ever.
Or even Tristram.. that chord. And Dechard Cain’s voice… EPIC!!

But I will have to say that, ironically enough, the MP3’s that made up the soundtrack for Heroes of might and magic 3, have made the background for countless hours of role playing sessions, as WinAmp was playing in the background, and that will have to be my choice..

I think the Everquest soundtrack from the 1999 release of the game is the most memorable. I LOVE the Kelethin music, and I also really love the music that plays in the deserts of north and south Ro.

honorable mentions would be, of course, Heroes 3 and Deus Ex.

My favorite soundtrack from a game is Morrowind.

The soundtrack is a perfect match with the game, and it really accompanies you during those long walks and the world exploration. The music is very calm and it helps you build this amazing atmosphere that this game has.

Risk of Rain 2

The Rain Formerly known as purple (name of the song)
i played on the loop everyday and never get bored

favorite soundtrack from video games: witcher3, its epic to me in that i can actually feel the soul/energy/dedication that the composer put into it. and i feel like i also wanna fight some monsters as well.