Design item Metro App for Windows 8: Is functional and feels natural on a system that has only a mouse or keyboard
Here is a list of items that are tested in your Windows 8 App. If you are in Southern California, please email these posts for more information on getting a token for your app by June 30, 2012!
Keyboard
Keyboard is still a very important input mechanism for Windows. You should ensure that your application works well for a user who is only using keyboard. This will require handling of navigation, tab stops, and ordering, etc.
Reference (HTML)
https://msdn.microsoft.com/en-us/library/windows/apps/hh750315
Reference (XAML)
https://msdn.microsoft.com/en-us/library/windows/apps/hh750315