Hi, everyone welcome to something. I've somewhat creatively titled in the director's chair
Well my flair for naming sub series of my video is open to debate
The name is aimed at reinforcing a point in
This video and others to come I'm going to talk about director systems in their impact upon video games
unlike our traditional perceptions of AI involvement in games
Directors are different and that they oversee or perhaps more appropriately direct the experience that the player has while playing a given game
For this inaugural video we focus on arguably the most famous of director systems which is found in Valve's Left 4 Dead
We'll start by talking about what directors are and how they impact the world
followed by discussing Left 4 Dead itself before breaking down how the AI director guides gameplay
In case you've never played the game Left 4 Dead is a 4 player online cooperative shooter. Set you're a zombie apocalypse
The goal is to reach the end of a series of maps that Define a given episode of play
Players are able to wield a variety of firearms and explosives in their arsenal with Melee weapons introduced in Left 4 Dead 2
The Crux of the Gameplay is reliant upon players within a given team to work together to survive against a large number of zombie threats
This can mean providing cover fire saving them when under heavy attack and sharing medical supplies such as pain pills and med kits
While, this is the core tenets of play
It's reinforced courtesy of the game's dynamic and often unpredictable
behavior. Surprise attacks by zombies are frequent and often very hard to predict this often results in
circumstances that only occur in that particular run of gameplay. I'd argue that from a Gameplay standpoint
This is the game's biggest strength and the players have unique stories of events that took place within that particular episode
No, two gameplay sessions are the same and that helps bring players back again and again
Much like in film or theater a director system is tasked with ensuring
Actors know their roles and play the appropriate part when creating a particular scene however
Unlike most directors
Director AI does not have full control of all the actors in the scene since human players
Have a habit of doing whatever they want in
Addition the audience for the show are actually the active participants of the experience
As a result, directors are focused on modifying the world around the player to continue to make it interesting and
This is sort of at odds with a lot of the AI we've seen in this series thus far
Given that it's often manifested physically in the world as a non-player character instead the director oversees
What is happening in the game and makes changes to the state that satisfy some base requirement?
Often a director is interested in
Managing what we will refer to as the flow of gameplay we want to manage the intensity of play such that it peaks and troughs
Creating periods of gameplay which has a very high intensity
This is when a director will typically meet gradual changes that start to make the gameplay more dramatic
During which things will just go to [beep] and you'll need to bring your a-game
Of course we can't have the game run at high intensity at all times
it becomes a lot more stressful and players ultimately need a respite
Otherwise they'll simply burn out and may in fact turn the game off
as such the director will recognize after certain a period of time the intensity should start to reduce and make changes to the game or
could actually be doing nothing to allow the player to start to catch their breath
Of course once the players had a long enough respite these peaks of Intensity should return
It's important that these peaks and troughs are not always the same strength
Meaning that the intensity of Gameplay will continue to fluctuate
And reach maximum peaks perhaps on more than one occasion as we proceed through a given level
The exciting and often hard to predict gameplay is driven by Left 4 Dead's Director
An AI agent who directly manipulates the current state of the game world and an effort to keep players under duress
This is a crucial component of the game
Given that it helps maintain a sense of urgency in players
it reinforces that you can't stay in the same place for too long
There's a need to keep moving and pay attention to what's happening around you
So how does the director achieve that?
What's important to appreciate is that the AI behind the director isn't interested necessarily in killing players or
winning the game. It doesn't treat the game in such an adversarial fashion
Rather its focus is to maintain pace
Now at first this may seem a bit odd
But this is the principle behind which all of Left 4 Dead is built
The game is built on a repeated sequence of events that have an impact upon the game's intensity, and it's broken up as follows
Part 1 - 'The build up'
The director realizes that players aren't really under any sort of duress
As such the game increases the intensity level and focuses this on particular players
Part 2 - 'The peak'
Director recognizes that the intensity levels exceeded a particular threshold as such it makes one last play to keep those players under pressure
Part 3 - 'The relax phase'
Knowing that it needs to ease up the director ramps down
What is exciting about this phase is it's now waiting to repeat the cycle
When it decides to do so can be dependent on a number of factors
Personally I love the fact that is watching you play and waiting for the right moment to start attacking once more
These three activities comprise one epoch of play and the game will continue these peaks and troughs of intensity with varying strengths and
frequency
the interesting part is that this intensity is measured by assessing the stress level, or the perceived stress level of the player and
That's largely focused on the number of zombies attacking players and the proximity with which they reach them
The more zombies at close range the more their stress levels are perceived to increase
Furthermore if a special infected is able to attack a player and in doing so pin them down, the stress level reach maximum
These are measured on a per player basis meaning that the director will focus on players if their stress levels are lower than others
So how does a director change the game world to accommodate?
In short, it adds zombies to the map as you move through it
In actual fact when you start the game the map's empty
The director then decides to start adding zombies into the map in order to provide a challenge this starts with the wanderers
Individual zombies are simply roaming around on their own
These are placed on the main path of the map and will attack you if you get too close
Meanwhile mobs larger groups of zombies are added in groups of ten to Thirty at a time
These will often come from the side of the map or at least off the main path directly in front of you
That's designed not only to keep your guard up
But to ensure that you seldom see them coming
the Director maintains a budget system
From which observes how many zombies are in the map and will either add or delete them as necessary if the number of zombies on
screen goes below a particular threshold and its objective at that time is to increase intensity. It will add more wanderers, mobs, or special infected
Each type of zombie has some sort of condition that dictates how it can be entered into the game
While we already mentioned the regular zombies the special infected are equally constrained the specials not with the hunter jockey [better]
Boomer charger and smoker are restricted such that only a handful of them can be on the map at any given point in time
In addition only one of each type can be on the map at once
This is designed to ensure a sense of balance
That you're not being wiped out for example by a horde of Hunters
Equally these restrictions ensure that players have a chance to defend themselves or rescue others. It doesn't mean the players will succeed
But at least they're given a fighting chance
Lastly the boss zombies the tank and the which can only spawn at certain specific locations as determined by the designers
Do these spawn points are deliberately awkward and that they force you into confrontations?
While the which can still be avoided if you move quietly and refrain from disturbing up the tank is unavoidable
In fact this is because the tank will always attack players once any line of sight is established
This is to prevent the player from being able to Avoid the tank which was actually possible in earlier builds of the game
However one [small] consolation is that once these events take place?
The director will refrain from adding more zombies otherwise it would prove too chaotic for most players to Handle
Nice to see [it's] considerate that way isn't it?
While the director is largely focused [on] the zombie spawning the system does make other changes to the game
item spawns are placed based upon a collection of preset [locations] set by the
Developers though the system will also swap out certain items based on Player performance in addition
There are also some more subtle changes to levels as well as the audio that plays in the background
The director communicates with a separate audio manager and players can begin to protect patterns of behavior in the game based upon
What audio is played the most obvious cue is that of the tank given the change of music?
I
Don't think I'd be kidding. That's [my] [pastime] as tankless oh
However, similar cues for other events exist [you] just have to listen very carefully
Lastly the director is not always in charge of the game
Several points of each level will result the director being turned off
To allow players to either move through a particular story sequence or prepare them for a major event such as the episode finale
However when these events take place the system can be led to go a little nuts and this can sometimes result in Rather Sadistic behavior
With masses of zombies spawning in well one or even two tanks are in the same map
The directress system of Left4dead has driven to an inspiration for a number of similar approaches that have appeared in other [Triple-a] games
Notably far cry 3 and recently Far cry 4 and even less violent or Aggressive games such as rocksmith 2014
Where an AI director observes the player playing guitar during the session mode and provides a backing band to accompany you?
But for now, that's it for this AI in games video
We've survived the zombie horde don't forget to read [the] written piece. Which is linked to in the description, and we'll see you next [time]
you