As part of todays keynote, Epic Games showed a brief tech demo of the Unreal Engine 3 running on an iPhone. In a surprise twist of events, this very same tech demo just appeared on the App Store mere moments ago as a free universal app. If youve got an iPhone 4, iPhone 3GS, 3rd Generation iPod touch, or iPad, feast your eyes on Epic Citadel [Free].

The 82.2MB tech demo includes a medieval town to explore, complete with a bizarre and a "mysterious cathedral". If youve been waiting to see just what the latest-generation iOS lineup of devices is capable of, you really need to check this out. Epic Citadel is a fantastic display of the potential of future gaming on the platform, as it has been developed using the exact same tools and technology that developers are using now to create high-end console games.