Hi Ian, I had some interesting problems, grin. I am using dev 8. I was testing out the zombie house, and when I realized that the structures do not have a blocks_sight flag, I thought I could try putting terrain under it that would do that. Stupidly, It didn't occur to me that the block sight flag would remain on the terrain, so the zombies killed three weak walls and then stood around, lol. I took out the block sight terrain under the weak walls, and they attacked the walls and could see my guy...but still do not move forward that round. I added blocks_sight to the wall terrain, and it was so cool. I was able to "see" outside windows which were terrain, but were not blocking sight, so you could look out a window, see outside just like in real life, whilet he walls block the sight everywhere else. My first problem is that structures can move onto tiles with blocks sight terrain, but once on that terrain, even with the flying tag, they cannot see out of it, thus the doors and gates can't close if they are on a wall when starting, more or less the "open" position. So essentiallyI am not sure what to do. I have to play further into the map, but I am thinking that some of the zombies might spawn outside sight range, and so stand still. So I think I am going to have to give them a sight_range of 100. If the player units are in the house, I am not sure if the distant spawning zombies will see them or react to them otherwise since the bad guys on this map are coming to the player units and not the other way around. Just some food for thought. al "The truth will set you free" Jesus Christ of Nazareth 33A.D.