This song is a scene song, rather than one that pertains to a specific place in the game. It is used for tense, neutral dialogue scenes for the most part, and for the most part keeps its shades rather grey. This is one of two songs used for similar scenes. Many games use only one song for such scenes, but with how bloody long this one is going to be, I could probably use three or four! :V
Anyway, yes, it is blues music in a very, very odd variation on the 4/4 scale. I didn't change it very much from the initial version I wrote in 2010. This is also one of the songs that plays in all 4 seasons of the game! The more you know*