Hi Bastian, I only looked a little at UDK. But my guess is that you can use FBX just the same way with UDK as anything else. But T2's FBX will only take A few things; Cameras, lights, this stuff.
You can extract the terrain just like before.
One thing you will want to look into for a TG2 terrain in UDK is "Mesh lab". A recent thread explains how you can reduce the file size of the terrain, in this way it may be usable in UDK. But remember that a UDK workflow expects you to be as poly light as is possible. And TG2 is for film, which does not really care about file sizes the way game pipelines do.
But I do understand why you would want to use T2 to create a game environment, the results you could possibly get are way nicer than most game terrains. The cooperation between software is the main problem though. You will probably need a program like Maya to be a middle man if you are going to do more than just experiment.
Im not a game maker, others will know much better than I do. But I think what I have told you is mostly correct.
