Thank you for playing, and for your feedback!
Those are all very good points. Most of those things are being worked on right now for the v2.1 update, but some I hadn't considered. Always good to have a fresh pair of eyes.
Indeed, the game could definitely use some aesthetic variation, but my primary concern at first was just to make a working game. I plan to add particle-effect-trails to the blocks as they move/collide, and it might be nice to change the palette of the rooms every ten levels. The lava is a purposeful juxtaposition to the ice - though it is never stated in the game, the character is meant to be traversing the "Puzzle Volcano." Now that I think about it, I don't know where that idea came from. Playing your game made me think I should experiment with the interplay of ice and fire a bit more in future updates.
Good point about walking speed - I will add a "toggle run" option.
I had planned a mechanic that caused blocks to turn 90 degrees, but somehow that fell by the wayside during my chaotic workflow.
As for the out-of-place easy levels... yeah, I'm not sure why I never moved those earlier. And level 25 and 26, I had initially thought were slightly different solutions, but upon further testing I realized that they were, indeed, identical except for the block colors switching. Oops! I will definitely add reordering and quality control to the v2.1 to-do list. That last level was poorly conceived as a vain attempt to place my little puzzle guy among the pantheon of video game legends, as well as startle the player with the sudden immensity of the room - but it did end up being mostly tedious and easy. It needs reworked, for sure.
Oh, and I forget if I mentioned this, but I sent you 2 free keys on FaceBook to share with whomever you please, as thanks for your generous donation.
Thanks again, and stay tuned - v2.1 will add more levels for no extra charge (Christmas-themed!).