Whew. Alright, now that a certain game-breaking bug is fixed, I can give this a proper review.
On the surface, it looks very basic; you're a rectangle, and you move to the green square. Looking a little deeper, you soon discover the importance of its minimalism as a physics-based platformer... narrow corridors you can only pass in one particular orientation, momentum-based walljumping, etc. None of the levels itself are particularly hard, but the ones that are difficult aren't as such because of the player being inundated by random bullshit at the worst times; this game is very precise, such that some of the corridors you have to pass through only have so much clearance space, and too much or too little momentum can throw off your entire plan if you're trying to avoid the "lava" that surrounds many pathways.
That said, nothing in this game is insurmountable. The game does boast to be hard, and it is in certain places, but it's mostly a mechanical difficulty. If you have bad reflexes or coordination, some levels will take you longer to beat than others, but you will eventually beat it.