I like the designs of the shadows. There's a nice contrast in design between the shadow you control and the shadows that come after.
Now that I got a chance to play in the levels, I think the controls shine the best in the flat horizontal levels where you can take advantage of your speed and dash. The vertical movement is extremely difficult to work with as you drop too quickly. This becomes a problem on the later levels, as reaching higher platforms requires being at the absolute peak of your double jumps, or in the case of 8-1, lining up the the character's hit box to go between the set of spikes. This makes the vertical element of the controls feel unreliable, which is detrimental for a precision platformer where you need to have confidence in all aspects of your manoeuvrability. Introducing some leeway on such sections, as well as having the downward acceleration from gravity be gradual instead of immediately falling at near full speed would make the vertical component of the movement feel consistent and controllable.
The level layout designs were quite interesting, especially levels 6 and 7 where the variety of starting points starts showing up. I think a nice addition to have would be a reset button for a restarting the current stage from level 1 in order to give them a chance to plan things out better. It's a shame that the spikes were only used in the last stage.
The controls could use some improvements, but I still enjoyed the game and it's varied levels.