Obligatory "not an expert, grain of salt". I had fun with this game, it was certainly an interesting exploration and the custom sprites solidified the atmosphere.
Spoilers
Gameplay: I really liked the tape puzzle and the inclusion of a map even if it was a little unnecessary once I was on the right track. It seems the "continue game" feature wasn't working, which was very frustrating as it took me a good number of goes to get the maze right and I had to mash through dialogue. I also have the suspicion that the game is near impossible if you choose any item but the lamp, the book, in particular is useless without the continue button working.
Story: A lot was left to the reader's imagination with the story, being very vague. The interactions with other characters were very interesting, and it certainly left me wondering about the relationship between the player, what was buried and the others in the mine. A little bit of a weird continuity issue as the cave-in is miraculously cleared when you go to leave the mine.
Presentation: This was some of your strongest points. I really like your animated thumbnail and the personality of your icons. I do think some more ambient noise would have strengthened your atmosphere, and some of the effects don't seem to quite line up. The door lock sounds slimy and crackly, it sounded organic to me.
Horror: Nothing really made me jump out of my skin, but there was a good sense of dread, confusion and claustrophobia conveyed by the sprite work, the dialogue and the darkness.
Theme: I'd say you knocked it out of the park, hit all three bonuses clearly and encapsulated being in the depths of the earth perfectly.
Conclusion: An nice exploration of the concept! Keen for future work!