Story was good! Seeing the effects of your actions, especially at the end, felt incredibly satisfying.
Art looked great and helped contribute to a sense of loneliness and then to a feeling of restoring beauty.
I do feel the first platforming trial got a little too unforgiving since you had to traverse a long series of falling platforms using a jump without air control. Eventually, I got used to it and was able to overcome it.
For the second trial, it helped that you automatically collected the first crystal right at the gate so you knew what you needed to do. I do think the gate could have been drawn in a way that it was more obvious there were empty slots. In other games with big doors, the slots would be all in or around the middle. I also think a little more challenge with double jumping would have been appreciated there.
Overall, good stuff!