Recommendation: remove the swipe controls, or at least decrease their sensitivity. It’s too easy to accidentally “swipe up from the bottom” to switch cubes, when all you wanted was to tap the bottom to move the block down. I would make the “switch cubes” command be a “tap” in the middle area, between the move left and move right tap areas. Switches are a much less common input than move left/right, so needing to stretch a bit to reach the middle to do that command is fine. Or, you could split the bottom touch area in half; one half is move down, the other is switch cubes.
Otherwise: excellent tutorial screen for showing the commands. Runs on my Android device at least.