Unreal Engine 4 is coming to Windows RT and Windows Phone. Someday. That's the word from Epic Games co-founder and CEO Tim Sweeney. The new game engine saw its initial release just last week for PC, and while iOS and Android are up next for Unreal Engine 4 development, they're also keeping their eyes on the mobile operating systems out of Redmond.
Said Sweeney on the Unreal Engine Forums:
We have been doing some work in this direction (implementing various levels of WinRT API support) and we want to have Windows Phone support eventually, but we're a very long way from having a ship-quality implementation.
Right now our mobile efforts are really focused on iOS and Android based on their huge market sizes. We have a lot of work to do on these platforms before expanding to other mobile platforms such as WP.
Now that's no guarantee that Unreal Engine 4 will come to the mobile Windows platforms any time soon. After all, Unreal Engine 3 was released in 2005 and was first demoed on a Windows RT tablet in 2012. But that Windows RT and Windows Phone are on the roadmap for Unreal is a positive sign, unlike other development houses that are quick to dismiss them due to their smaller (but growing) market share.