Beginning of Salvation, Horrible Village, Monologue - wow, they give the creepy feeling. If I was playing this game, I would unconsciously be turning my head back all the time to make sure there are no monsters behind me :) great atmosphere!
Sewers (Ambient) - the voices are really scary, love the bubbles and the overall sound design here as well
Rock and Stalagmites - I like the guitars here, so cool :) Music speeding up in the Underwater Serpent is niiice :)
Among the Boxes - the juicy kick here nice. National Emblem - great idea with the crows in the intro, developing of the music in this track keeps the listener's attention, nice work.
Rest Zone indeed gives it a break and lets the player rest for a while before the next fights. The rest is not calm though since the music does not let the player forget what a dangerous world he/she is in :) I think this is a good idea to introduce such a track as a change
Chaotic Stage - I like it how you mix synths with strings here. This track is cool
My personal favorites are Underwater Serpent, National Emblem, Chaotic Stage, Rock and Stalagmites :)
This is insane how much efforts you put in the work; sound design is amazing, rock/metal and industrial vibe is really cool. All tracks are different but still they fit in the chosen theme and style. This is amazing how many details are there in each track. Mixture of genres is interesting. This is a unique and very creative soundtrack, and it would definitely fit the game you imagined :)