Simple enough,
list a song found in a video game that gives you THAT chill up your spine. That truly unique song that transcends the game in itself.
Post only songs coming from video games and tell us why you post it.
I'll start with this one:
I recently started a new game in FFX. The intro song slapped me right in the face. How could I forget such a masterful piece. IMO, probably one of the greatest work of Nobuo Uematsu, music composer for most of Final Fantasy titles.