Played through the game, very fun. Got some thoughts on the difficulty.
I felt like the dragon was the first level where I really had to plan ahead. I got him after 4 or 5 tries, but I kinda felt like it was RNG. So I tried to beat the dragon again, to see if I could do it consistently.
I've beat it 4 times now and I feel like I figured out the strategy. I think it's not entirely RNG-driven and I could easily do it again now. This tells me the dragon is way harder than the rest of the game, and there ought to be some more levels leading up to it.
I saw a comment that 3-2 felt really hard and I'm inclined to agree. I think it's the combination of needing to dig for special shield blocks by raising the screen, and an enemy attack that adds a lot of blocks to one column at once. SO ANYWAYS I tried playing that level a bunch too and I was able to not only get consistent at it, but I beat it without taking damage once.
That said, the game is remarkably fair if you practice enough, though I do have some gripes about RNG. Perhaps 10 seconds is slightly to short of a time frame? I'd do some tuning there. Maybe reduce the time per turn if the player chooses Hard mode? My only real complaint about this demo is the difficulty curve, but that's typical of a game jam game. Fantastic game guys!