This is a continuation of the original Unreal Tournament engine. It is based on several parts from different sources:
The partial source code release to version 432: http://unreal.epicgames.com/ (site offline)
The OpenUT project: http://openut.sourceforge.net/
Chris Dohnal's work on OpenGLDrv and D3D9Drv: http://www.cwdohnal.com/utglr/
Original work done here.
This means that what you will find here is not the complete source code to the Unreal Tournament engine. Only some very specific parts have been open-sourced. However, there is plenty to improve on.
The goal is to get Unreal Tournament running smoothly on modern systems.
For now, this project is codenamed Surreal.
WHAT IS THIS???
(credit goes to SilverSound finding it and sharing on the UT99org Discord)