Randomization of level structure, Left 4 Dead

As we know, Valve has announced that in Left 4 Dead 2, depending on how well or poor your team is playing, the director may change the level to assist or hinder you. What Valve hasn't announced is that you can set the AI director up to do this in Left 4 Dead 1. For those of you who may question this, refer to No Mercy 3. Turn left directly out of the safe room, and right at the dead end, until you're standing in front of that truck. The door here is occasionally open. Why is this? By using a handy method of scripting within the game, the level designer can inadvertently create level modifications prior to the player reaching that level. There are entities that can be placed, which, based on certain circumstances met could be carried over to the next level, at least their properties, and whether or not certain conditions were met or not. However, you can take this one step further and, with a handy work around with the scripting, make the director seem just as advanced as AI Director 2.0. With a little work of triggers and logic relays, you can have the game change the layout, add items, remove items, etc, etc., based on time or other variables, such as player health, among things. While currently buggy, I've produced this method in my upcoming campaign. I've produced changes in the environment that I am sure will surely surprise you.