This is going really well! I dig it. Did you do the environment tiles, too? Looks awesome.
Hope you don't mind the lack of feedback around here. That's what happens when you post work that's better than 90% of posts. The level of quality doesn't leave a whole lotta room for crit. But that's GOOD news, for you.
If you're keen on posting regularly about this project as you go I might suggest doing so in the Devlogs board instead -
https://pixelation.org/index.php?board=27.0Overall, this is working quite well visually, imo. Crazy good for someone's first isometric environment attempt.
Has any code been written yet? Typically you want to get a working prototype up and running asap, before finished art assets are needed, but that's a different subject. Or maybe you're just practicing iso pixel art techniques.
It does look cool essentially, but I don't really understand what all the white drippy stuff is. If it's paint, then the painters were insane and they need to go back to wall paintin' school. It reminds me of glitched pixels or redraw garbage. That said, it does make the brick walls much more interesting. But I wish I could tell what it's supposed to be.
I'm really interested in your 3D workflow.
What is your pipeline like for going from 3D to 2D, specifically the pixel conversion stage - when the rendered 3D animation gets turned into a pixel art animation.
What about squash/stretch, adding wind-up frames to increase impact, and smears for weapon swinging frames?
These things are inherently difficult to pull off with rigged 3D character animation, so I'm guessing you have a plan to incorporate such enhancements in your animated sprites during the pixel art redrawing stage.
Idea - black out walls cross sections and remove noisey edge highlight, too.

Will walls' visibility be toggled when player walks behind them so he doesn't get lost?
Have you thought about adding dynamic lighting or other non indexed pixel art effects (NPA)?