Really cool idea complimented by a stylish minimalist art style. I struggled with the first couple of puzzles as I figured out the rules, but got the hang of it soon enough.
I will say there were still times where the rules didn't quite work as expected: sometimes the 2D view was still impacted by the Z-axis of the 3D view (Cubey would miss a platform in 2D because he wasn't in line with it on the 3D plane). Or a platform I felt I should've been able to jump on in 3D wouldn't let me land on it.
A slower onboarding to all the rules and concepts would serve this game really well if you were to expand it. For example, a few small rooms just about the white boarders before, then a room or two where it's just 3D shifting, then rooms that start combining both. Understand it's not always feasible to have so many levels in the timespan of a game jam, though.
Nicely done, still! I had a good time with this :)