Epic Citadel is a tech demo from Epic Games that is meant to illustrate the endless possibilities for Unreal Engine 3 in a mobile environment.
Epic Games is, of course, the high profile studio behind the success story that is the Infinity Blade series on iOS devices.
Android has had precious few games that could actually utilize the incredibly powerful Unreal Engine, and Epic Games wants to make it easier for Android devs to license the Unreal Engine with the help of Epic Citadel.
Epic Citadel is not exactly a game. Instead, it is a peek into the beautiful and detailed game environments that are used in the likes of iOS games such as Infinity Blade. It has a Benchmarking Mode that can let you know how your device is coping up with performance sapping graphic elements such as dynamic lighting and reflections.
However, as promising as all this may sound, Epic Games has made it very clear that it has no plans to bring Infinity Blade to Android whatsoever. Disappointing as that may sound, it is a clear improvement on the current scenario where, apart from dev behemoths such as Gameloft and Square Enix, no Android developers want to risk spending license fees on demanding games based on UE3 all thanks to rampant fragmentation.
You can have a look at how your Android device can cope up with high end graphics by downloading Epic Citadel from Google Play.