I love difficult platformers but I'm not a big fan of this one, I simply don't enjoy the controls and focus on linear platforming around slippery surfaces. The art, animations and style is fantastic though.
I also don't see the reason why hard mode exists, after running out the time the first time I just beat the game on easy instead, after which I went through hard mode thinking there be some difference but there is nothing different at all except for the timer. Other than that I think the timed mechanics not resetting when you die is kinda annoying too.
I also noticed that you posted before about levels and block types that aren't part of the demo (like the last gif on the game page), did you cut those intentionally from the demo or what?