After the last Major update on the end of February 2015 we decided that we didn't like the user interface [menus, task manager, achievements menu...] very much, so I started to redesign the whole UI from the scratch.
Finally I've just finished with the new UI for iOS version!!! [April 31 2015]
All the code for the new UI is a custom code in Unity without the help of GUI layer or the new Unity UI system. After experimenting a few days with the Unity new UI system I found that it was too risky at that stage to use it. So I build some custom classes to manage a custom UI system with dynamic capabilities for multiple screen sizes.
Check out for the new update and have fun!