After playing this game for a while I have one thing that bugs me a little -- the faces on each cube are arranged randomly.
I feel that if the faces had fixed positions like on a dice, then it would take a certain amount of mental skill to decide what way to rotate them in order to get the color you need in the quickest possible way. As it is now, your best bet is some combination that rotates through all possible faces, and then hoping the color you want isn't on the last face.
Perhaps having a fixed ordering would result in issues with the gameplay, and I guess you are randomly distributing only the number of colors needed for the level. I don't really know how, or if, that would work. Is it something you considered during development?
Or well, perhaps I am getting too old to move my fingers fast enough. I've seen my son play Geometry Dash, and spent five minutes slamming into the first three obstacles before realizing I wasn't meant to play that type of game anymore