Unreal Engine 3 (UE3) is a real-time 3D game engine developed by Epic Games. It was first released on October 29, 2004, as part of the Unreal Tournament 2004 package.

UE3’s development began in the early 2000s, when Epic Games was working on the next version of their popular Unreal Engine. The company aimed to create a powerful engine that could handle more complex graphics and physics simulations, as well as provide developers with more control over the rendering process.

In addition to its advanced graphics capabilities, UE3 also introduced several new features, including support for dynamic lighting and shadow mapping, real-time lighting, and physics-based animation. It also included a number of improvements over its predecessor, Unreal Engine 2, such as better performance, more robust scripting tools, and improved multiplayer support.

UE3 quickly became popular among game developers, with many high-profile games being developed using the engine, including Gears of War, Crysis, and Uncharted. It also gained a large community of developers who contributed to its open-source version, known as the Unreal Engine SDK.

Overall, UE3 played an important role in the mid-2000s tech revolution, helping to drive advancements in real-time graphics and physics simulations, and paving the way for more immersive and interactive gaming experiences.