I like the spacey vibe at the beginning. The wave-like pattern of the synths is definitely on-brand. The pacing is a bit slow, but I like the call-and-response high-pitched synth line at 1:33. The quickening pace of the synth line at around 2:00 helps give the piece a sense of direction, although the transition at 2:20 still felt a tad abrupt, as did the entrance of the bass at 2:28. The heavier drums and synth guitar at 3:10 or so are a nice break from the mostly atmospheric content of the first 3 minutes. The texture is still pretty thin harmonically, but the blissful melodies at around 4:10 help thicken it up a bit. Sometimes, during the busier sections of the piece, the drums are struggling to come through the mix, like at around 5:30. I also think the "The city" section drags on for a bit too long without much variety in the instruments or harmonies.

I like the more melancholy tone of the piece by around 7:00, although the transition into 8:00 could've been a bit smoother. The piano melodies there are a highlight of the piece for me, although at 8:52 the chords sounded a bit clunky. It might help to space the notes out a little more so they have a more open, well-balanced sound. The rich pads at 9:30ish are a treat, although some more filtering or automation could've added some interest at times, especially to maximize the emotional appeal of the piano at 10:17. The wonky progression at 11:02 is really engaging, and the organ and frantic drums that come in shortly thereafter really give that section a sinister undertone. This is another place where the drums are a bit too quiet in the mix, though - I might give the organ a little less space in the lower-end of the frequency range in the equalizer. The drums might also need a boost in the mid-range with a multi-band compressor. The melodies at 12:33 are killer, although they also could stand a boost in the mix vis-a-vis the pads and harmonies.

13:20 is one of your better transitions in the piece, and I love the drum solo at 13:34 and the catchy low-register piano line at 14:06. The section at 14:53 sounds like a jabbering bird indeed, although the fade-out into 15:39 was a bit underwhelming of a conclusion to that section, even though it's on-theme. The gradual fade-in at 16:20 is nice - I really like the atmosphere and sound design of that part, from the floaty synth arpeggios to the murky pad at 17:08. The last 5.5 minutes of this piece would actually function well as a stand-alone track in my opinion. The gradual build-up of tension into 18:40 is really effective, and the rhythmic syncopations blend really nicely together. The melodies at 19:50 serve as a nice point of arrival, although a lot of the harmonies are ducking under the mix during the downbeats at that section. Again, it couldn't hurt to clear out some of the low-end frequencies there or even pull back on the reverb. The dense final chord at 21:07 is nice - the grating treble range of that organ adds a bit of tension to the otherwise resolutive tonic, as if the journeyman's journey is not truly over. :)

Overall, I think you've focused a lot on the overarching narrative aspects of this piece, which isn't a bad thing, but it could use a bit more ebb and flow within some of the individual sections, just to keep the listener engaged more. Vocals might help make some of the thematic elements of the track come alive, especially during the "argument" section, which, it should be noted, is my favorite of the piece. Given the overall energy level and dynamism of the melodies, I think the argument section could even be a fitting conclusion for the piece as a whole. If I was going to do a "radio edit" of this piece, I would probably make an "Argument/Old Man is a Bird/Argument" sandwich, if that makes sense.

Anyway, I commend you for a strong and ambitious track here, Cavernsparten. A little more variety in some of the individual sections and some cleaner mixing in places would help take it to the next level, but overall the sound design, atmosphere, rhythmic content, and narrative elements of it are really impressive. Keep it up! ^_^

Damn a 20 minute song is actually kind of insane