I read through the other posts about this and they seem to be saying different things on this subject...

If I create an box in my map, the skulk can climb it,

if I make that box either func_wall, func_illusionary, func_seethrough, or a dozen others I've tried, the skulk can't seem to climb on it no matter what I do...

What is really confusing me is that I have downloaded a sample map that someone else made in hammer and he has both a func_wall AND and a func_seethrough entity that the skulks can walk on....

Can anyone explain whatever finer point here that I am missing?

You'll have to make a clipbrush (brush textured with CLIP) covering it.

would this also work for Sky? i don't want skulks walking on my sky texture. so just create a brush texture with CLIP?

ok then, what can't they walk on?

Have a look here for tips for outdoor maps/areas:

http://www.unknownworlds.com/forums/in...showtopic=62266

it is also listed in the mapping faq btw

Kouji, i've read that and it's helpful, but this section was VERY vague

I mean place a brush near the sky which blocks the skulk so it can't reach the sky.

Also what I didnt mention but was mentioned in this thread. You can make use of a trigger_push and place this entity over the sky brush. Set its angle(yaw) to down, now when a skulk is trying to walk along the sky he'll get pushed away. As a matter of fact he can't even touch the sky.
Just don't overdo it on the push speed since you don't want them to be catapluted across the level (I think even a value of 1 is enough)