The AI Director is the focal point of both Left 4 Dead games. He controls when and where hordes appear, what path to take, and what items you will recieve. His instinct is a controlled chaos with a sick and nice side as an illusory gentleman. Sometimes he will be very forgiving and other times he will be sick and twisted. Though he has a pattern, and once you unlock it's secrets; you can master Left 4 Dead.

The Director's base mood revolves around what difficulty you play on. His mood is subject to change depending on what you do in the game.

In easy, he is much forgiving, spoiling you with good items. Hordes are rare as you will be blasting through the campaign in a matter on minutes. Most SI are in predictable places and are easy to spot.

In normal, he acts as you've played the game before and gives good items when you really need it. When things get too easy, he will drop in a horde or two to slow you down. SI spawn rarely in noticable areas.

In advanced, he is very strained and will sometimes reward items. He drops in hordes unexpectedly when things seem more clean than usual. The good items will be placed around in different places so you may have to scatter. SI are hard to predict and will sometimes suprise the player.

In expert, he is very impatient and does not reward you with the best items. If you take too long, he will drop in a horde for being too slow. Items are always scattered and if he even gives you a good item, it's usually a friendly fire trap (i.e. the grenade launcher) or a reward for doing well in the game.

The Director will reward or punish you for various actions in the game. The effects of these will take place in the next chapter or in a map restart. (Where all survivors die.)

He will give out better items if you progress with difficulty. Friendly fire results in more infected to be spawned. If you struggle to keep up with the team, he will attack the straggler; this also applies to rushers. If you are doing too well in the game, he breaks the action with a tank. If you teamkill, he spawns in more hordes and sabotages items. When two or less survivors are alive, he spawns infected at streched intervals; however, he makes the hordles last longer. If a player looks ahead of the map for items, (Using free cam while dead,) he will no longer assist the survivors and make it harder.

In short, for every bad action, he gives a bad response. For every good action, he gives a better response. Be careful what you do, he is always aware of how well a team behaves.

In certain campaigns, the Director will have a choice of what path to allow the survivors to take.

If the survivors are progressing through the campaign at a fast rate, he will make the path more complex. If the survivors are struggling, he will make the path more linear.

These effects are entirely different in realism. He will always randomize the path in realism and make it hard for the survivors to progress.

• The director gives out first aid kits every time you heal a survivor.

Wrong. He rewards better items for actions you do. Not first aid kits. Not to mention, these effects take place after every level transition. So if your team was cooperating and giving each-other items when needed on a campaign, you are rewarded next level.

• The director's effects take place on Versus.

No. He is limited on versus. He will mainly spawn hordes and items on versus and that's it. He will not reward or punish survivors for their behavior. He will in some circumstances spawn a tank around the saferoom if the survivors are griefing by not leaving. Also he will unlock the saferoom door if they take too long to leave. (Allowing infected to spawn.)

• The director has feelings?

The director doesn't exactly have 'feelings' but he has a script that alters his spawning behavior based on teamwork of the survivors. Feelings would be an easier term instead of just mentioning that, as saying "a script that alters his behavior blah blah blah" a few times gets very tedious.

• Is the director the God of L4D?

A God is defined as such: "a superhuman being or spirit worshiped as having power over nature or human fortunes; a deity."
He could be considered the God of L4D, controlling all outcomes of the game, and deciding how to treat spawn cycles in a match. Also considered he is able to create things like infected and spawning items. However, he is nothing worshipped by people; therefore he is not a god. Just a line of code. He has a cult following after several years.

Special thanks to user Baby [NL] for all this info. (http://steamproxy.net/id/girlygirlgamer)

There are levels where the AI might choose not to spawn a tank, and there are levels where there is always a tank. The last level in No Mercy before the finale, with the elevator panic event, always has a tank. If you didn't get the tank before the elevator, you'll get it afterwards, regardless of how poorly you are doing. The only time I've seen this not happen was on easy or when the tank fell off the building.

There are several clues as to what the director will do next. In dead air, 2nd level, after climbing the fire stairs into the apartments there is a bed there with weapons on it. If it doesn't have a combat- or autoshotgun, then there is a witch pretty nearby. Other spawn spots for single weapons in the game tend to offer you a hunting rifle or a military sniper rifle if there is a tank right ahead. There are lots more tricks like this; one should always focus on getting a "feel" for the game's rhythm.

If there is a spawn spot like a closet or whatever, once you open it, nothing else will spawn there (only exception used to be dead survivors, and even there I'm not sure if this hasn't been patched). This means that if you're pretty healthy, but a tank is up ahead (judging by the sounds) and you have a spawn spot with a door right there, you should open it AFTER you killed the tank and the team took damage, because that way you have a better chance of finding goodies inside. One such spawn spot for example is in the tunnel of love in the dark carnival campaign.

There is a predictability to who the AI will send the zombies after next; it has to do with the AI's perception of your stress levels. It's doctored in a way to not let anyone get bored, but at the same time not to make it so hard for any one survivor that he or she would rage quit. If you are already chased by a (burning) witch, chances of you also being smoked or hunted drop dramatically. If you were the one saving your teammates from the last smoker, hunter, jockey and charger - congratulations, you're up next on the hit list. If, on the other hand, you just got attacked by three or four infected in a row, relax, that smoker is probably going after one of your teammates unless you just really happen to be a very easy prey.

There is a cap on how many infected the AI can spawn. There are multiple panic events that you can essentially run through if you throw a bile bomb behind or below you (not into a fire) because the AI won't be able to spawn more zombies. 2. There is a predictability to the spawning of pills - but less so for healthkits, unless it is a level that has infected survivor zombies who drop items. Have no pills on you and two teammates in the yellow or red, and you'll usually get pills; this is why you should use pills before healthkits on most levels.

In the plantation finale, besides that standing by the machine gun is a deathtrap, it also seems to yield more special infecteds than staying on top of the bushes by the gate or at the secondary stairs at the back. The same thing goes for "crash course" at the fire-the-horowitz crescendo event; running back downhill into the garage seems to make for less horde spawning. It's possible this is not intentional, but instead the result of the AI director not spawning hordes in spawn spots that are directly visible to the survivors, or other errors. In the boathouse finale, tanks used to sometimes die after spawning if you set at the dock or the rocks; same in the no mercy rooftop finale, if you sat behind the airco tower. I think they patched both in l4d2.

Thanks for reading this guide, and if you have more information to add, please let me know in the comments below.

-Uberkiller