Thanks! And yeah, I've gotten the suggestion to ramp up difficulty faster from a few people.

Although interestingly some other people in the comments here say they liked how the progression goes.

And that's an interesting little game you made.

And I spent quite some time creating an algorithm and solver to find the par for Unflip. I'm planning to release a blog post about it soon

I think if you make the par visible in the "result screen" and add a "try again" option to "next" this could make it more interesting without the need to ramp up difficulty. I think I solved a few cases with a bunch of random shifts, for example, and may have switched to thinking mode if I was faced with that.