The concept is really neat and the visuals are quite cool. 

However, I was quite confused about what the actual mechanics of the game were (I still played through all the levels, but pretty much by brute forcing them). The walls seemed inconsistent to me, with some allowing only the white cube to move through, and some allowed neither, without much indication of which they are or how it worked. Originally I thought it was how the shadows were overlapping or something, but in the second level there doesn't seem to be much reason why the white cube can walk through three of the five walls but not the other two.

I'd love to hear what the mechanic was behind this if you're willing to share because I'm guessing I just didn't understand it.

This definitely is one of my favorites this jam! Such a simple concept that turns simple levels into a mystery slowly revealed. Love it!