The game packs a lot of ambience for what seems a minimalist design at first glance.
Regarding the difficulty spike mentioned by others, I want to add the context/defense that while, yes, the complexity would suddenly ramp up, each underlying mechanic was properly introduced beforehand. We were never overwhelmed with new info or even thrown two new things at once. I do not see any flaw in the design. Though I guess a gentler difficulty curve could retain more players, which is far more important than what I think.
Feature suggestions that I would have personally benefitted a lot from after getting stuck and needing to come back a different day:
- Level checkpoints.
- Limited-use (once per restart?) undo button.
But I understand how that second one could be seen as undermining the challenge of the puzzle.
This may be intentional design, but:

Block C moves when I push B but block A did not despite the link.
“Est. playtime: 10 minutes” Is this a taunt? Do you wanna fight