More a general mapping question than portal really.

How did they do the blue fade effect seen in the last escape level?

http://www.thebighand.co.uk/blue%20fade.jpg

I am guessing its some kind of func_brush, but playing around with various render modes has gotten me nowhere. There are fog entities but these seem more complex, and running that bsp through vmex results in a map that crashes hammer.

Probably just your standard fade distance, with a blue fade color setting.

It's a fog entity, almost certainly. (env_fog_controller)
with a colour of roughly 130 180 200, and a high fog end number

Its not actually that complex, the only keyvaules you need to use are

"fog enable" - yes or no
"fog start" - how close to your eye it starts (inches)
"fog end" - how far away it stops
"primary fog colour" - colour at the front?
"secondary fog colour" - colour at the back?

hope that helps

Turns out that level does use an env_fog_controller, but I was hoping to only use it for one room, not the whole level. However it also has inputs so I can turn to fog on and off, will have to experiment.