Unity 4 is now available for both Windows Store AND Windows Phone 8 app developers as an open beta! Already some games are published using the game engine platform, my favorites being Big Buck Hunter for Windows 8 and Fling Theory for both Windows Store and Windows Phone.
Register for beta programs, check the list of games already built to the Stores and read the disclaimers about how ready the platforms are below. The Windows Phone version is the more recent one, so that’s obviously the less mature one as well.
- Windows 8: http://blogs.unity3d.com/2013/
03/07/ unity-4-early-access-for-window s-store-apps/
- Windows Phone 8:http://blogs.unity3d.com/2013/
03/27/ unity-4-beta-program-for-window s-phone-apps/