Come play Unreal with us then hehehe

May I present to you, a tool called Err

Indeed it is a great port. The engine is incredibly optimized and very well made.

Lots of hand optimization for occlusion calculations (reminiscent of Crash Bandicoot)

I posted a comment on the video - I made a patch for this game to allow for looking with the right stick and the cheat menu during single player (with some added debug options).