Really great idea! Reads really well with the clean visual style. However, I think the double jump isn't that well explained. It's a kind of mechanic that rarely is in games, so having it be so integral to gameplay without explanation caused me a lot of confusion. As well, a lot of the puzzle are just dealing with small scrolling/falling spaces with spikes, and I think that with stronger puzzle design, your fantastic concept could shine even more. I hope you continue this project into a full title!