"What's the Unreal Engine 3?" the laymen asks? From the press release: "The Unreal Engine has been designed to ease content creation and programming, with the goal of putting as much power as possible in the hands of artists with minimal programmer assistance; and to give programmers a highly modular and extensive framework for building, testing, and shipping games in a wide range of genres."
What's a modular framework? You're on your own.
[Update 1: corrected game titles using Unreal Engine 3]