Vidilian

I feel the midrange (and to some extent the upper treble) here is fairly cluttered when we get to 0:46. It seems like the brass, FM pads, and vox are competing there. What I would recommend is to scoop the midrange a few dB on the brass, and try low passing the FM pads (the buzzy part) a little so that the vox can breathe.
The cause of the muddiness that Hemophiliac hears is the clash of the sub bass and the low end hit like at 0:30 - 0:32, in the 20 - 120 Hz range (although the low-mids don't actually have much going on). I would try sidechaining a small amount so that the low end hit there pushes down the sub bass when it strikes. I would also consider high passing the sub bass so that you cut out anything below about 20-30 Hz - it usually won't make a difference on what you hear, but it'll help with the overcompression by clearing up some headroom.
Hope this helps the mixing!

Consider shortening the length of the bass notes (or maybe it's a low pad) so that they aren't playing as much.  Similar to how you have it at 1:28 and after.  It will help give space to the other parts, and sounds much better.  I'm not sure what it is, but the beat isn't gelling with me for some reason and i'm not sure why.  Consider adding a hi-hat to it to help fill the space maybe?
Changing the lead sound at 0:23 is a good call.  Switching up the lead to other instruments is a good way to keep the listener interested.

Evaluation:
Don't worry about the vocals sounding robotic.  They fit in the genre that you're going for.  Interesting source, haven't heard it before; thanks for sharing it!
It doesn't feel fully developed yet even though the original is short.  It feels like there is still space for more exploration and development with yours coming in at 1:49.
Low end does feel muddy as the bass takes up a lot of space, make sure you're applying EQ on it to remove unnecessary frequencies on it and EQing any reverb that may be on the bass as well.

After Measure 26, at 0:46 when everything comes back the track gets very full and looks like you really pushed the levels to be as loud as possible.  Gotta keep some space in there for all elements to come through and have breathing space.  You could achieve this with remixing the levels or through utilizing compression to duck certain elements out of the way.  It's during this section that the percussion gets nearly buried completely and can barely make it out.  You want to have the mix look more like the first half in the image above, you can see all of the peaks clearly and there's space for all of the elements.
Does the vox have a lower harmony?  It sounds like there's something maybe a 5th below the melody line, but I can barely make it out.
Maybe try looking for another track that sounds similar to what you're going for here and reference it.  Using comparison could help you clean up the mix if you really listen critically.

The sounds are quite harsh, considering it's a fairly mellow arrangement. The piano right out of the gate is very jarring - definitely work on humanising and expressing that part a little more naturally, and dropping the volume in the mix. The synth in the background 00:14-00:45 sounds a bit like a bagpipe as well - not particularly pleasant to my ear. It gets much nicer from 00:47 with that trancey-style synth dripping in delay, and those nice bells, however the bagpipe soon comes back!
I like the arrangement at the moment, but the sound design could be a lot better. Consider sculpting your synths more with EQ and filtering, maybe add some more voices to the synth, phasing and LFO panning/extra width to envelop the listener in the atmosphere.

I like the arrangement of this mix. However, there are some issues with the instrument/drum choices.
Let's start with the drums.
First off is the initial kick. It is over powering the mix, causing it to stand out. If you only used the softer kick starting at 0:40, that would be much better. Second is the hi hat. I like the panning, but it is too loud, try lowering it just a bit.
Now onto the instruments. Alot of the are very soundfonty and midi like. Almost like you played them through a 90s roland midi machine. Very vanilla, ie: they have no fx added to it to make them fuller.
With some good FX mixing, you can even make that sax sound good. Everything just sounds like it's being played raw in a sound studio.
 
Lastly, is the how some sections sound very bare. In some areas (mostly the 1:01 to 1:40 mark), it sounds bare. But this may be from synth/fx choices. There just doesn't sound like there is enough going on with that bass and drum beat moving the mix along. I really like the break at 1:46 to 2:04 though. 
You have a good foundation in the arrangement, but needs some more work. Good start!

The reverb your using makes everything sound like they're a bit too much in the distance. Increasing the pre-delay on it should bring things more to the front while still keeping the sense of space. You may need tone down the reverb a little as well. Also, try and double track the rhythm guitar to see that helps them sound more substantial.
Also, arrangement-wise, I'm struggling to pick out elements from the original, like the melody, in your remix for some reason. That may be because your changing things up so much or because I'm being dumb.

I looked up how LMMS works and it's similar to what I'm used to. You should use the FX mixer for your reverb instead of putting one on all your tracks seperately. Send the signal of the tracks that need reverb to an FX channel that has the reverb on it. That should let you then eq the reverb FX channel so that the reverb is cleaner for all the tracks you're sending to it. Probably not explaining that well but hopefully you understand.

I looked up how LMMS works and it's similar to what I'm used to. You should use the FX mixer for your reverb instead of putting one on all your tracks seperately. Send the signal of the tracks that need reverb to an FX channel that has the reverb on it. That should let you then eq the reverb FX channel so that the reverb is cleaner for all the tracks you're sending to it. Probably not explaining that well but hopefully you understand.

Reverb is also tends to be a thing you need to clean up with EQ, just like the instruments themselves. I'm not to familiar with how LMMS works or how you implemented the reverb on the tracks, but if there's a way for you to tweak the frequencies of the reverb (removing some low end, etc) the you should look into that too. Overall, you've definitely improved the EQ for the instruments from what I remember last time though. Keep it up

Reverb is also tends to be a thing you need to clean up with EQ, just like the instruments themselves. I'm not to familiar with how LMMS works or how you implemented the reverb on the tracks, but if there's a way for you to tweak the frequencies of the reverb (removing some low end, etc) the you should look into that too. Overall, you've definitely improved the EQ for the instruments from what I remember last time though. Keep it up

One thing that I recommend, if you're not doing already, is importing a well mixed song that's roughly similar to what you want yours to sound like and using it as a bit of a reference when mixing. It'll help you gauge certain things about your mix, especially as a beginner. It'll also help with the issue you mention about the mix sounding vastly different on different speakers. You can use the reference track to let you know roughly how your song should sound when going between different devices. 

One thing that I recommend, if you're not doing already, is importing a well mixed song that's roughly similar to what you want yours to sound like and using it as a bit of a reference when mixing. It'll help you gauge certain things about your mix, especially as a beginner. It'll also help with the issue you mention about the mix sounding vastly different on different speakers. You can use the reference track to let you know roughly how your song should sound when going between different devices. 

I thought I commented on this. Not really sure what the scale is. At 4:17, in the original track, I hear three chords play. It's sort of a subtle glissando. That may not be the correct musical term. I guess you can say the notes are a tad more humanized rather than three notes pressing down at the same time. So I wrote out what I hear, and maybe you'd like to throw it into your remix. Someone with a better ear could probably tell you the correct notes. I'm not saying yours are wrong. In your remix, you only have the final note being played, which I believe are A, E, and then D.
Overall, I like the direction you took from the original. It still has that qualm feeling. This Divine Beast was one of my favorites, as well as the boss, but I felt unsure of what I was supposed to be doing.

From what I can tell, the original doesn't just use notes from  a normal diatonic scale, but I can find it hard figuring out some songs so I could be wrong. Will extend it later.
Remix: https://sites.google.com/site/vspaine/wips/Unholy Thunder M.mp3?attredirects=0&d=1
Originals: 
 

You're not working on this much more so I'll just point out the main thing that stood out to me. The synth that plays melody at 0:45 could cut through the mix more, especially when you compare it to the next synth that continues the melody at 1:00 which is much clearer and fits into the mix better.