Unreal have just released a new complete game + tutorial Match 3 Game for Unreal 4.10. It is currently available for download in the learn section of the Epic Game Launcher.
This is actually a pretty impressive example project as it illustrates:
- UMG UI Graphics
- Paper2D Toolset
- Blueprint and C++ Code
- in app purchases
So basically most of the functionality required of a modern 2D game. You can learn more about the release here or download the sample game on the Android store (iOS coming soon). The entire project weighs in at about 120MB. You can also learn more about the sample (and other Unreal Engine things) in the Unreal Engine live stream video: