“The Extension Pack for UnrealTournament Classic is a huge Bundle/SDK full of new features, methods and tools improving the Unreal Engine 1 in a wide range. Next to tons of new visual features it improves overall physics (has it’s own build-in Physics Engine “Thelema Physics” or short “TPhys”), has loads of gameplay and AI enhancements, a new render (currently OpenGL only) to deal with hardcoded features and bundled tools. However this is really not the first attempt of improving an old engine, the initial spark for this SDK came from the concept of the “DoomsDay Engine” and the content of this Pack that was archived before it’s public announcement when it’s elderly features were used for the Mod “Lost Secrets of Na Pali”.”

Release/Progress Details

• Public Beta/Preview Version: 17th October 2007 (100 % done)
• Public Final Version: TBD (Around May) 2008 (73 % done)

Source: www.moddb.com/mods/9974/unrealtournament-extension-pack

Here you can download the Demo Version of the Extension Pack for UT99. It contains mostly new basic features like Emitters and Lensflares and can be seen as some kind of Preview but not as an SDK like the Final Version.

Unreal Tournament SDK Forum

Download UT Extension Pack v1.0:
Downloads -> Updates