absolutely love that tune and Empire as an album .....had a listen with headphones on to the first 2 minutes or so ......sounds like it's all Key of E on 4 string to me!
your first riff is a bar of 16th notes on G# (4th fret low E) followed by open low E for a bar of 16th notes ......look for B (2nd fret A string), C# (4th fret A string), F# (2nd fret Low E) for other chords in the tune!
