Xamarin + Universal Windows Platform
Xamarin lets you build C# apps for Windows, Android, and iOS.
Whether you just want to share back-end code between your Xamarin apps and Windows, or you want a complete shared-code solution for iOS, Android, and Windows Phone, Xamarin helps you achieve your cross-platform goals.
Xamarin.Forms for Windows and UWP
Xamarin.Forms lets you share not only logic but user-interface code across platforms. We now support iOS, Android, and Windows Phone 8.1, Windows 8.1, and the Universal Windows Platform (UWP) for Windows 10 too!
Cross-Platform Code Sharing
Choose Portable Class Libraries or Shared Projects to contain the common code, and use them in Xamarin.iOS, Xamarin.Android, and Xamarin.Mac projects, as well as the Universal Windows Platform (UWP), WPF, WinRT, or other C#-based platforms.