Hugh from NS2HD visiting Unknown Worlds Entertainment takes a look at the concept art he found around the office, You may see some things you have never seen before :)
Couple of videos: This is a look at the drawings found on the walls of the office:
Hugh goes through a book he found that was presented to valve containing early concepts and the basic idea of the game... The Art Compendium
I loved that, I got really excited when he cited the dynamic infestation!
As a modeler myself, concept art is naturally neat to me. But NS2 concept art is just damn well beautiful.
especially love the 3 marines getting through that door behind the glass.
Brilliant!