Coming from R4R. Wow, this is nothing like I usually listen to and I'm not familiar with the songs that you have remixed, so hopefully I can give you some sort of meaningful view. If I must be honest, I actually have no idea what remixing involves, so I can't comment on how well you've done it, but it sounds flawless.
You create a uneasy atmosphere in the intro with some very interesting sound design. Curious to know what you did there, but I like it.
Overall the mix sounds pretty damn good. I'm really digging the sparse, dark atmosphere of the song and the slow build up. Each element you add sits nicely in the mix and there's little clutter. When you add something new, it takes the forefront and something else drops out, so it never feels messy, but there's always something to maintain interest in the mammoth of a song. Your melodies don't demand attention and remain subtle and I enjoy that. I actually envy it a little because I have a habit of wanting to make the melody the centre piece of my music and it prevents it from being too atmospheric in the way yours is (could totally picture your song in a game)
The change around 5:00 is good too. Enjoying the change in the rhythmic and percussive aspects of the song. Again, it feels like everything has been thought out and well placed in the mix. Nothing is there that shouldn't be there -- you aren't adding things to fill up space. I'm writing this review as I listen, I'm 7 minutes in and am in no way bored yet which is a feat within itself.
I haven't said anything bad yet. I don't even know what to criticise. I'm enjoying every aspect of this, from the musicality, to the production, from the sound design to the composition. You've done a great job here. Feel like I could learn a lot from you (if you have any resources to share, I'd love to see them!). I often feel like music in a similar vein shies away from elements of tradition composition, like melody and harmony and instead focus more on the percussive aspect of the music, but you've incorporated both the nerdier production side of music with the "traditional" aspects.
Great work! Looking forward to hearing more from you! :)