WordRoom started as a Windows Phone project, the third client we started to develop and the first one we released was for Windows 8. We developed the windows 8 relative fast because we could reuse a lot of the code from the Windows Phone project in that we used portal library for the core logic.
As I mentioned above, Windows 8 was the third client we started to develop. The second was for android devices. I started to build the android client with java and eclipse. Step one was to translate all core logic from C# to java, a lot of work but I developed an almost finished client for WordRoom. But in the end of 2012 when we should start to develop the client for iOS we decided to use and mono touch and mono for android from Xamarin so that we could use the same assemblies for the core logic that we did when developing for the Windows platforms. We also share data contract assemblies between the backend and the clients. So now we running the same code in at backend in Windows Azure, on Windows 8, Windows Phone, Android and iOS.
The decision to start using mono is one of the best decision we have taken. We saving a lot of time and we get an app that is much easier to maintain.
Next app I will develop I will think about that that the code will be shared between different platforms earlier in the process. Because if you have a structure in your project with GUI and business/game logic split up and using interfaces for platform specific features, for example local storage you can reuse much more code and save a lot of time.