Hi! New composer here! Need opinions!

alright, hi!
i took a look at all of them, and i want to preface this by saying they were all great tracks. and that because i dont have very much experience in this field, my comments might not be the best. but this is what I had to say anyways!

1. "Maria of the Realm" - Part II
I enjoyed the mood this one provoked - very tense. Additionally, certain parts were very reminiscent of some of the battle themes from Shining Force for the Sega Genesis, which has one of the BEST OSTS EVAARRR. No, but seriously. I really liked listening to this one. The percussion was fitting and kept the song progressing nicely. I also liked the "calm down" part that happened right before it picked up again. It helped to keep things interesting. Piano melody was great too! Don't really have any complaints for this one! Definitely my favorite though.

2. "The Great Dome"
Oh man, this one. Hearing this for the first time, I immediately pictured the protagonists of a video game in the process of discovering something like the antagonist's palace. This did a great job of foreshadowing that something was to come. The percussion helped to play a big part in that. Also, the string section was smooth, and the vocal/choir part was super interesting. The guitar chord that was played just as everything started to pick up was super fitting. My only complaint was that I wanted to hear more!

3. "Assault on Sirendia"
This track provoked an interesting mood to me. I pictured the main character of a video game hearing news that his home is being invaded by the antagonist's evil army - and is rushing back as quickly as he/she can (on horse of course) to try and repel the threat before there's nothing left. Once again, excellent, tense track. The percussion and the string section work together to create a feeling of unbelievable urgency. My only (minor, minor) complaint is that around the 15 second mark, there's a part that seems maybe a bit too dissonant. Regardless, fantastic track!

4. "Flower of Peace"
The chord progression and the melody on this one is great. I imagine it being played right after the big, final battle; (Warning: cheesiness inbound) where so much life has been destroyed - but at the same time, there's new life to come (or something like that, you know?) and all our characters can do is count their losses and move on. It's a very bittersweet feeling, and I enjoy it immensely. My only complaint is during the second strain, (with the arpeggiated chords in the left hand) it sounded a wee bit too choppy. I'd imagine that it would benefit from some sustain pedal or maybe even a slight increase on the release? Really great tune anyways.

5. "Smooth Line"
Oh, this track is just fun. I immediately imagined it being played as you fight the New Age Retro Hippies from EarthBound. The bass and the drumbeat is very disco-esque, which contrasts with the instrumentation used in the melody. Don't really have any complaints with it! Melody was fine, actually the bass was pretty melodic too! Overall a good, fun track.

6. "Nocturnal Land"
I enjoyed this one too. The percussion in the first part reminded me once again of Shining Force. The melody in the flute was nice, and I thought the counter melody in the cello was fantastic. It definitely seems fitting for an adventure setting! To me, it would be the first journey the protagonist embarks on with his companions. Nothing too serious is at stake, which I think kind of reflects the happy go lucky sound of this song.

7. "Maria of the Realm" - Part 1
Like the second, this was a tense sounding track. I liked the brass stabs that occur periodically, it helps to keep the tense feeling alive. The super fast melody in the piano at the beginning invokes a very urgent feeling as well. The nylon guitar (?) part was an interesting addition, if not a wee bit out of place. String section kept everything flowing nicely. Again, a fine track!

8. "What We Must Do"
This one! It kind of has a desperate feel to it, but I can't put my finger on it. Something similar played during the hard fights in Dragon Ball Z maybe? Don't completely remember. Electric guitar part was good, drums were good. It was just a solid track in my opinion. Wish I could've heard more of it!

Well, that was quite the listening experience overall! I think you're a great composer!
To answer the "what is lacking question" I don't know man. I think a lot of people end up asking this question, myself included. I guess maybe we'll always ask ourselves this. Maybe it's because we always think we can do better? I really don't know. It's a hard question to answer. I don't think your songs are lacking anything really, but I kind of see what you are saying.

I would also love to hear more fast paced orchestral pieces! You seem to be great at writing those. Although, I would also love to hear more pieces like the "Flower of Peace" one.

It's been a pleasure to write and listen to your tracks! Thanks again