I played through the first chapter and a couple levels of the second. These sorts of rotational combination puzzles usually give me fits, but I feel like I'm actually starting to understand out how to think about it. So I'd say the progression seems good to me so far.

When dragging, it's unclear to me how it decides which center to rotate around when there's a choice. It doesn't seem like it's just distance from the center. It has a tendency to rotate the one I wasn't thinking of. Maybe the game is trying to tell me something?

It doesn't show me which stars I got when I complete the level; it only shows them when looking at the chapter/level select screen.
It took me a little fiddling around to realize what "M:" and "R:" were ("moves" and "spaces rotated", right?). Maybe you should give them longer labels? Or explain them at some point? Actually I'm not sure why you have the second one at all...are you using it for scoring in some way?
And is it deliberate that the timer and the counters don't show up when you first play the level? I could see that you might be trying to make it more relaxing the first time through or something. But it would be nice if there was an option to always show it. Or maybe just have it retract into the edge of the screen, and have a little handle you could grab or click to slide it open or closed, and only do the current behavior if the user didn't leave it open last time?
As for your landing page...first off your IMGA acceptance video is hilarious. Not so professional, maybe, but I got a good laugh out of it.
I saw your "marketspeak-to-English" rationale for using "essentialistic", but my first reaction was, "That's not a real word!" Unless it's important to you, you might consider using a less esoteric word...
You need an apostrophe in "Prismatica's" at the beginning of the second paragraph under "About the Game". And I'm
almost positive that you want "aesthetic" instead of "aesthetical" there.
Otherwise it looks good to me.
Edit: Oh. After you complete a level, I
really want a "replay" button as well as the current "go on" and "chapter menu" buttons...
Edit edit: In level 1-03 (you have a screenshot above) it should be "colors between ax
es blend"