Still working on my Left 4 Dead 2 Survival level. It's an office building turned CEDA evacuation center, now abandoned and overrun. I've roughed out most the geometry, placed a few props and textured a bit. It's still missing something. I should have planned a little more before I jumped in to the editor. I had some thumbnail sketches of how I wanted it laid out, but it morphed as soon as I started laying out brushes. It feels a little claustrophobic, so I think I'll expand it, make the second story accessible, perhaps. It just needs some more polishing. Testing is a little cumbersome, since the nav mesh has to be rebuilt every time the geometry changes, so it's harder to jump in and test after making major changes to the map. There has to be a way to automatically fill in the gaps or update the nav mesh without deleting and adding by hand. I'll take another look through the documentation and browse some forums.