Diablo 2 Tristram Piano

Perfection.

I like FF XIII-2 heart of chaos.

https://www.youtube.com/watch?v=XhZKZF2u5HI

A second to the Bastion song, as well as Quest for Glory song (all this time I had thought it was called "Erana's Peace").

For my own post, one I'm surprised hasn't come up yet:
Jeremy Soule's Nerevar Rising

Which essentially set the trend for the next 20 years of ES soundtracks :D.

Well, given the time of year, I'll link this one from The 7th Guest/The 11th Hour:

Skeletons In My Closet

Kiss The Sky from Tales From The Borderlands always makes me smile.

https://www.youtube.com/watch?v=qZe7VeIc1JA

I generally prefer non-vocal game music (hence, the Bioshock tune in the first message bored me, while the Broforce menu music sounded great and gave me a few extra inches to my manhood), but since we are on that path, I present this great vocal song from GTA: San Andreas:

Heart: Barracuda

But as said, I don't really consider that as "game music", even if I happened to hear it the first time in a game.

While we are at it, maybe some game should add this great piece of music as its menu music or somesuch, just so that I could mention it in game music threads:

https://www.youtube.com/watch?v=BeRVBw__ThE

A Cruce Victoria from the Europa Universalis III soundtrack
https://www.youtube.com/watch?v=5cCB7nrhaKE

Oh, fully digitized Amiga music? I always considered that as bit of a cheating (as compared to "proper" tracker-type of MOD music on Amiga), but since you started:

Starglider pre-intro music (probably the first time I remember hearing digitized music in a video game, with vocals?)

Garrison (nice guitars)

Dirge for the Planet from S.T.A.L.K.E.R.: Shadow of Chernobyl.

I love the haunting melody of this song, and lyrically how it kind of tells the story of the game. Listening to it brings me back to all the good times I had wandering the Zone.

Make sure to listen to the very end for the quite possibly most passionate voice acting in gaming history.


Stronghold Crusader - Weasel Turd:

https://www.youtube.com/watch?v=g2DEpC2oMws

Not a song since there is no singing, but...
Diablo - Tristram

I honestly don't know if it's my favourite, but I do have a soft spot for Fight or Fight from Treasure Adventure Game (the Treasure Adventure World version is good as well, but I particularly like the one from the first game).

Like timppu above, I don't count licensed music as "game music", though I first heard Mr Mister's Broken Wings in GTA Vice City and it quickly became my favourite track among those offered on the game's radio stations, and I've listened to it many times since (even bought the vinyl album on the spot when I saw it in a store despite not having an LP player).

As there was already a post from the time waaaay back i have to add another one of that time:
not the original (which can be easily found on the other songs nearby this) but the live performed one
https://www.youtube.com/watch?v=PTSUR3RHh9M

Really hard to decide which one to pick. I'll go with this one then: Jeremy Soule's Peaceful Waters from Morrowind.