Chord progression analysis of Godhead's Lament

Wow, rather comprehensive. I've never tried to analyze an Opeth song seriously, maybe I should give one a try. Still Life has many highly complex chord progressions, but it somewhat lacks dynamics present in Ghost Reveries and Watershed. The transistions from part to part doesn't always work. This is especially true with White Cluster.
 
I still maintain that section I is in G major, since it resolves via the C-F# tritone (which is basically viidim of Gmaj and a very strong dominant function) to G. It just makes sense, since the next section is in Eminor, and it's a pretty common compositional technique to begin in a certain key and then quickly modulate to the relative major or minor.

Xarthaz, you're absolutely right... I should edit this and try again. I think what happened was I ran into a non-diatonic chord and got confused. I tried to treat it as a temporary modulation but I'm sure it's just a modal borrowing like you suggested.

Edit: It also looks like I screwed up in section 2; this part IS clearly in e minor. So the opening G in this section is treated as the III of eminor and it ends up resolving via a plagal cadence. That makes a heck of a lot more sense.
 
^ Regardless of the key, the beginning riff is a minor riff, just listen to it. Just trying playing the GMaj chord along to the beginning and you'll see that it doesn't work at all.
 
lol you know all these fancy music theory words and terminology, but you think the opening section is G major so you actually don't understand music theory whatsoever
 
^ it can be in a minor key without starting on a minor chord

That is without question BUT there is nothing major about the opening riff to Godhead's Lament. Don't want to make this into a "That's not a tritone-substitution it's a Lydian Dominant 6-5-1!!11123 ZOMG."