Metro App with 2D Graphics in C#

Question

I have done some looking and I can't figure out a good way to write a 2D tile/sprite based game in C# for Win8. According to the MSDN documentation:

You can use managed code languages like C# and Visual Basic to develop 2D (and lightweight 3D) games.

The problem is that I can't figure out how to do this. The reason I would like to use C# is because I already have a lot of code written for Windows Phone that I would like to reuse.

Can anyone point me to how I would write a fairly efficient 2D tile/sprite MetroUI game for Win8? The only thing I can find uses C++ and DirectX.

[EDIT]

To clarify I do not care too much what I use (WinRT, DirectX...) so long as I can submit to the app store, and write my code in C#.