Android Unity 3d experimental game : Cubi

I'm playing with Unity 3D and I'm coding a small game called "Cubi".
I published it on Google Play: https://play.google.com/store/apps/details?id=com.bartoleo.cubi
I'm trying also Startapp as a way to monetize it.
Sources available here: https://github.com/bartoleo/cubi

in-game image