For directions of the pieces could be a good idea to implement controls that appear directly on the piece itself, as small arrows that appear on the edges of the piece when is selected. The controls at the bottom of the screen are a bit confusing and uncomfortable (to me).
I actually planned them as transparent sprites. But after working one week for Z order, i believe they are buggy. I will try to implement better controls in next build, also i will add keyboard WASD and arrow key support for easy controls. If i could add touch control support it will be super easy but i don't have a device to test.