Although what they are using seems to be getting close to acheiving results, it is impossible to directly convert JK geometry to any brush-based engine (Half-Life, Quake(s), in fact any modern engine).
It would be best not to convert the levels, but base new levels on them that better fit the new physics engine and gameplay and expect number of players. I expect we will see about 1,000,000,000 Canyon Oasis 2's and Battle Ground Jedi 2's, so just pick the one that best fits your liking and play away.
- I am Oobiedoob Benobi. I have the Silliest name in the Galaxy.
- Whats your middle name?
- Scoobie Doobie.
- Oobiedoob Scoobie Doobie Benobi?