It is unofficial, fan made actually, but all feedback towards this version goes towards the Epic Games version.
Had some fun with it, very early alpha and they stated there will be near daily weekly updates.
They say to only download it if you give feedback, Sshhhh.
EDIT 1: Files down, servers down, sad faic.
EDIT 2: New solution, download the actual files https://forums.unrealtournament.com/showthread.php?12011-Unreal-Tournament-Pre-Alpha-Playable-Build, then download the launcher
https://forums.unrealtournament.com/showthread.php?11401-Non-Epic-Playtest-Feedback
Connect to a server, and you're golden.