"T H E U N D E R G R O U N D" - groovy! Mixing and mastering are top notch, so you've succeeded at training these aspects, nothing to suggest in this regard. The feeling is generally immersive (I liked that subtle choir, it added a lot of texture and some of that "this is our destiny!" feel).
"T H E M A C H I N E" - This one seems to be fitting for an intensive section, such as a chase or a battle. It sounds rebelious and bold, and those squeaks feel like the patience has ended. I feel like the drums are a little bit too loud, though, speaking of mixing. But great sound, you did good on this one.
"T H E R I O T" - feels very cinematic. It would be fitting for a cutscene of sorts. The chord progression though suggests that some violence is involved... Here, the drums are loud, but that plays in the general feeling of the song, so the mixing is perfect. Then we switch in a sort of "the final confrontation" mode - great job. (That sound at 1:25 though... I recognize it, hahaha.)
"T H E A F T E R M A T H" - feels liberating yet sad. I like how the birds oppose the synths/strings. It shows the beauty of nature(freedom) and that it was always present, yet we were the ones who overlayed it with all of the noise and left ourselves trapped. My headcanon is that the birds were present in every song, yet we only focused on all of the artificial tension, that didn't even matter.
Overall, great mixing and great journey, nothing to add. Take care!