I found this game really fun! I love that you kept the mechanics simple so that you could focus on content. Maybe I'll try that in my next jam!
Also really liked the combination of the different cube's powers.
As a feedback, I'd recommend making sure there's enough visual clues as to where you need to go. In level 3, for example, it took me a long time to figure out there were platforms high above that led to the plate.
I'd also move in favor of removing the necessity of holding X when finishing a stage to keep playing with the other cubes, and just have that be the default behavior.
But other than that, I really enjoyed it!