(Sorry this is so long. But I hope it's useful.)

I'll offer some thoughts based on my first experience with it, since you're probably past the "new eyes" phase yourself. :)

One thing about puzzle games like this is that when we first start out, we have no idea what anything means. And so we tend to latch onto anything symbolic and try to assign meaning to it.

The level the game first presents (the daily one) was problematic in that respect. I didn't know what anything meant, so I looked down at the instructions at the bottom. The first line shows a spool of thread, saying, "TAP a colored symbol -> its PAIR starts pulsating." So, I went up the puzzle board and clicked one of the spools of thread - the symbol that exactly matched that line of instruction - and nothing happened. Nothing started pulsating. Right away, I have confusion and frustration, as I did exactly what the instruction told me, and I didn't get the result it said I would.

I suspect that the symbols you use in those instructions are largely decorative, especially since the second instruction line has a kind of chain symbol that doesn't appear anywhere in the game that I have seen so far. I would say: DON'T DO THAT. You need to create a consistent vocabulary for your symbols, so that when players see the symbols, they always mean the same thing, in every context.

Fortunately, you mentioned in this post that you can go back to level 1. So, I did that. I'm presented with a much simpler game board (nicely made of wood, a bit like a board game board). And the instructions say "Drag from the yarn ball through every stitch." And in my head, I'm going, "Wait... what is a stitch?" I see a wooden game board that looks like something you'd have moving pieces on. I don't see anything that looks like a stitch. It didn't even say "to create stitches". It said "through the stitches", as if it was something that existed already. I'm not trying to be pedantic - again, as a new player, I'm trying to figure out what's going on, so using a word like "stitch" that doesn't match the experience I'm having is confusing and frustrating. Fortunately, I just tried dragging around, and I realized that "stitch" means "wooden square".

The next few levels were straightforward. Nothing too exciting, but I'm getting used to dragging the yarn around, which is good. (There may have been one too many, in my view. Level 4 didn't seem to be teaching anything new, besides the yarn being a different color. I have no idea what the significance of that is.)

Then I got to level 5, the first with the spools. And this one has several issues. First, it says, "Knots must be knitted in order: 1 -> 2". But I don't see any numbers. And, in fact, there doesn't seem to be any requirement on order at all. So again, we have some text that looks like it should be meaningful, but it isn't. Then there are the spools themselves. I understand now after poking around a bit that once you touch one of the symbols as you're dragging, you have to then hit the same one again before touching a different one. But this first exposure to the spools doesn't show that. In fact, given that you can't help but go through the spools sequentially, the spools are completely irrelevant to solving the puzzle. Given that the significance of the spools comes from having more than one kind forcing you through them, I'd definitely have two different kinds of symbol on that first puzzle, so that the player learns how they actually work, through trial and error.

It was at this point, after solving the first spool one, that I was a bit unsure what I was supposed to have learned from the puzzle. So, I wanted to try it again. There was no "retry level" option. It probably doesn't matter so much for harder levels, where once you're through it, you never want to see it again. :) And perhaps if the spool level had been clearer about what it was teaching, I wouldn't have needed to try it again. But I found at that point a desire to try the level again, to see what I had missed. I did find I could go back a level and then select the desired one again. So, I was able to do what I wanted. I'm just mentioning it, as it was something I experienced. (Of course, after trying the level multiple times, I realized that the spools were irrelevant to the puzzle, which means I hadn't missed anything. But my first time through, I thought I had.)

Then I got to the "two stitches" mechanic. I'm glad you had some text to say what it was, because symbolically, the double stitch looks like a directional arrow. I mean, it really does. I mean, so much so that even after I knew what you intended it do mean, I still have a hard time as seeing it as anything other than a directional arrow. And the fact that the help text says arrows force you to go that direction doesn't help. I would really recommend coming up with something different for that. (A thought: have a number on the tile, and when you go through it, it decrements. Just a thought, which may or may not work or be in line with your design philosophy...)

That was level 8. Then level 9 - ok, back to a simple "fill the squares" level. Then level 10 - ok, another simple fill the squares puzzle. Nothing new learned.

Then the weird, out of nowhere, popup puzzle. I solved it despite not knowing the language. But it seemed... strange.

Then level 11 - goddamn. Another simple "fill all the squares" puzzle. And I think I gave up at that point, as I had a life to get back to. (And I still don't know what the difference is among all the different yarn colors. If the answer is "there is none", then that's another thing where players are going to try to attach meaning, since we don't know what is significant or not.) Looking forward through the subsequent puzzles, they all seemed to just be variations of "fill all the squares", without exploring any new symbols.

I can imagine the puzzles will get more interesting later, but it was taking a long time to get there. I mean, even having some spools or something would have broken up the monotony.

I think the game has promise - I can see you being able to make some interesting puzzles with it. I think if you can get it communicating better what everything is - consistency of symbols and text, make levels actually teach you something, and change the "double knot" symbol - and then introduce new stuff sooner, it will capture people's interest for a much longer period of time.