Epic's Mark Rein's confirmed that Epic Citadel's been downloaded more than 1 million times from the App Store.
Epic Citadel is designed to show off Unreal Engine on iDevices.
As noted on Epic's site: "Players navigate a fictional castle realm using simple and intuitive touch controls. It’s all about exploring the world, from the circus bazaar to the bridge overlooking the river to the mysterious cathedral at the center of town. Look around, navigate the area and enjoy the dazzling visuals."
Rein also said via Twitter from Korea yesterday that, "The Unreal Development Kit (UDK) has is now over 350,000 installations which is pretty amazing for a game engine like ours."
Take a look at it, if you haven't already.
Rein also posted in the comments below that UDK will soon be made available for all iOS devices.
"We also announced that UDK, the free version of Unreal Engine 3, would soon allow developers to make apps for iOS devices," said the developer.
"That means this technology will be available to anyone. See www.udk.com to try it for yourself."
Supported devices are supported devices are iPhone 3GS, iPhone 4, 3rd gen iPod touch, 4th gen iPod touch and iPad.