JRH, I like what you have done here, but I didn't like the fact that once the plr steps in the zone that it is always fog, so I edited the script with full ambience(which for those that want can edit it). This new script will allow for the plr to say walk into the zone and then walk out of it. The ambience in the fog is set at 40 like you had it and when you walk out of it it goes back to 100. Enjoy and thanks for a great addition.
;Artificial Intelligence Script
;script by JRH
;edited by starmind001
;Header
desc = Apply fog effects
;Triggers
:state=0,plrwithinzone=1:state=1
:state=1,plrwithinzone=0:state=2
:state=1:fog=1,fogblue=255,fogred=255,foggreen=255
:state=1:ambience=40,ambienceblue=0,ambiencered=0,ambiencegreen=0
:state=2:fog=0,fogblue=0,fogred=0,foggreen=0
:state=2:ambience=100,ambienceblue=255,ambiencered=255,ambiencegreen=255
:state=2:state=0
;End of Script