First off, you really nailed the "forest" vibe here. I got the sense of being in a forest or jungle of some sort, surrounded by bamboo and mist in a way where I can't see everything around me due to the density of the foliage.
The second half in particular has just the right amount of tension. I get the sense that if I were a character in this game it would seem like there is a real threat somewhere nearby. I'm imagining, I can't see the threat, nor do I know exactly what it is, but it's making the hair stand up on the back of my neck. I need to run away, immediately.
If I were rating this on how much I liked it, I'd give it 5 stars because of the immersion alone, no question. However, the way I review is based not on my own taste as much as it is how effective I think your intent came across.
With that in mind, I have some notes. First, the imagery I get from this, while very immersive and accurate, doesn't completely match the scenario IMO. The background sound design in particular, especially throughout the first part before the tempo picks up, makes me think of a very warm climate, rather than a snowy one. Also, there isn't a lot in this piece to make me think this scenario takes place at night, which, from what I gather from your description, it is supposed to.
Other than those points, I think you did a fantastic job accomplishing what you set out to do. It's easy to see why this was frontpaged.
More info about how I review music here: https://codefreq.newgrounds.com/news/post/1089806