Wow, these are great! I really like the juxtaposition of the orchestral and 8-bit instrumentation. It's makes sense conceptually but it also sounds really cool in a way that is pleasing to my ears. Granted I haven't listened to a lot of entries yet, but this approach to the theme seems well thought out and creative and I liked reading your ideas about the imaginary game.
Also interesting how your main theme (DCBA was it?) is a descending motif when your whole soundtrack is about climbing a mountain, but there was enough ascending musical material throughout that my analytical brain wasn't too conflicted about this discovery. :) (In my mountain theme I was extremely on the nose with continually ascending scales, not subtle at all.)
Dangerous Puzzles didn't seem to fit with the rest of the tracks somehow. I feel like it's supposed to relate to the other songs but it's just not hitting me. Like I feel like I'm suddenly off the mountain and in a jazz club? Maybe could use more strings haha. Anyway these are my impressions. Great work!