Ok, so you asked for criticism, which I'm going to take as an opportunity to nitpick a little bit (from one guy who dabbles around with music composition/arrangements to another). Also fair warning, I do most of my stuff from ear as I only have a bit of formal training by the way of music theory (and I've honestly forgotten most everything by now), so none of what I have to say will be very technical
First of all, I've got to say, the piece overall sounds pretty cool the vast majority of the time, and I'll echo what a few other people have said that it sounds like boss fight music; there's kind of a creeping dread to it, and at times there's dissonance that really builds into that feeling of unease. However, something that you need to understand (and I think you actually started figuring out, because it became less of an issue as the piece went on) is that dissonance nearly always needs to go somewhere, you can't just toss chords that clash into the middle of a measure and "hope for the best," you need to take the time to listen to the chords surrounding it and think to yourself about whether it "works" or not. I felt like the worst offender in this category was whatever you were using as your "reverb" harmony instrument, there were times when that particular track did things that I felt just really didn't match up with what the rhythm and melody tracks were (both of which I honestly thought were brilliant otherwise, if not a touch repetitive).
A bit of advice in that regard, though; notes don't ALWAYS need to change, don't feel like just because you have a pattern of one track playing 8th notes rhythmically while the rest only change once per measure that you can't switch things up a bit. One of my favorite tactics is to hold a note on one instrument while letting another change around that one - this is where you could add in a bit of dissonance at the end, so that you can change both at the same time to resolve to a "satisfying" chord. As it stands, I feel like you're tempted to try to hit a different note each measure with every instrument, and I suspect that that's you trying to create a faster feeling for the piece, but... there are times that that works, and times it doesn't, and if it's clearly not then consider shifting things around a half step or so and trying again, or even just not changing one instrument from the previous measure (remember that just because you haven't changed THAT instrument, that the chord structure itself hasn't changed)
Otherwise, though, I do think that it's a very solid first dive into original music composition. And again, that was me being nit-picky, because you specifically asked for criticism and I want to help you work out the kinks so this can be the best version you want to create; and to that end, you're free to take or leave any advice that I offered