A Day In The Life:
AI Designer

By Joe
"Adus" Hegarty, style="font-style: italic; color: rgb(255, 255, 0);">Artificial
Intelligence Designer, Funcom

My name is Joe "Adus" Hegarty and I'm an AI designer for Level 1 - 40
Content in Age of Conan. Typically, a day at the office for me consists
of creating and maintaining NPC AI, Item-Interaction, and some internal
tools for AI Designers.



One of the important things we have tried to do with Age of Conan is
create Non-Player Characters (NPCs) that actually have a life and
unique behavior. We’ve done several things to make this
realistic and it adds a tremendous amount of depth to the game.



City
Life



The thing I have particularly enjoyed working on is the so
called “City Life” aspect of the game.



One of the most interesting things I have personally worked on is the
children in Old Tarantia. They run about playing during the day (as
children do), but once nightfall is reached, their parents will come
out the collect them. The obvious “just 10 more
minutes”-type argument ensues before they finally admit
defeat and actually go inside. They will then remain inside until the
following morning. The system we use for this is based on the actual
day/night cycles we have in nearly all areas of the game.



Elsewhere, we have NPCs conversing about world events, husbands and
wives arguing over alcohol, preachers in front of crowds and guards
talking about how quiet their day has been. Such conversations have no
direct impact on the player, but they add an interesting aspect to the
game and I have found it exciting running around the world listening to
the conversations our very talented writing team have cooked up for us.




For example, a merchant might travel between two towns through
treacherous territory protected by body guards. Alternately, a group of
NPCs might launch a raid on an enemy camp—as early on in
Tortage, when you’ll stumble on Picts raiding the very
poachers trying to kill you! The possibilities here are endless and the
entire team has tried very hard to cram in as much as we can!



Epic
Events



Epic events are world events that happen regardless of what a player
does.



You can be happily running around the world and get caught in an
invasion between two rival NPC factions. One example of this is in
Sanctum of the Burning Souls, when the player walks in on a full-scene
battle between two rival NPC groups. The player can choose to help the
“good guys” or just watch.



We’ve worked closely with our writers and quest designers to
ensure these events are steeped in Hyborian lore and feel authentic.



Quest
Events & Lore



In partnership with our Gameplay and Quest Designers, we
have several events based on quests and lore from the game. These range
from simple ambushes to full scale single-player instances entirely
controlled by AI Scripts. You will meet Kalanthes, Zelata, Conan
himself, and battle the minions of Thoth Amon. We have AI that runs
when in dialogue with an NPC and numerous cutscenes to immerse the
player in the world lore.



Personally, one of my favourite scripted events involves debating a
point with an NPC Preacher in front of the crowd. As you select
options, the crowd reacts to your choices. There are 3 possible
outcomes to the quest based on what the played chooses to do.



We feel that these type of quests are new to the MMO scene and we hope
that players will enjoy playing them as much as we have.



Needs



NPCs do not simply stand around waiting to be attacked. They might
patrol an area normally, but grab food when they are hungry, hold a
conversation when they feel the need to be social, or actively seek out
enemies when they get ambitious. This is achieved with a needs system
that NPCs must satisfy when living in the Hyborian world. 



In order to make this system realistic to an observing player, we
attach priorities to each need the NPC has. Not all NPCs have the same
needs, and how often they must be satisfied varies.



For instance, an NPC is more interested in defending itself than
talking to another NPC. The system is also dynamic and can be
interrupted at any point, so if an NPC is attacked when he is talking
he will immediately defend himself.



To achieve this we use a combination of several technologies, these
are: Event Priority Tables, Maslovian Pyramids, Scripts and Brains.



The
System



Now it’s time for me to geek out about what I do and go into
the gory details of how our system works



Our scripting system does not simply control NPC AI. It’s the
system we use to glue the design and code together.



The highest level of configuration for an NPC is its
brain—this is the most obvious and visible part of the AI
system—which controls the NPC and its actions. The brain
allows us to configure what action the NPC will perform in certain
situations. The core of these are called the senses, which are modelled
on our basic human senses. This include sight (NPCs have a line of
sight, like players, which means it’s possible to hide from
them and for them to spot you) and hearing, among others. The brain
also “listens” for other things going on in the
world, such as other NPCs calling for help, friends and allied NPCs
being attacked within the line of sight, and even detecting players
healing the NPC’s current target.



Underneath the brain is the Maslovian Pyramid, based on
Maslow’s hierarchy of needs. You can read the long version href="http://en.wikipedia.org/wiki/Maslow_hierarchy_of_needs"
target="_blank">here , but the short version is
that our NPCs are motivated by basic needs, and only when those needs
are met will they move up the “pyramid” to higher
level functions. For example, an NPC being attacked will obviously not
be concerned with going to get a drink, while an NPC that has been safe
for a while may decide to go talk to a friend, go look for trouble,
wander back to his hut and sit down, and so on. This pyramid glues
together the different needs for a given NPC and sets up the Event
Priority Tables to tell the NPC what its concerns should be. The Event
Priority Tabels set up a response to a certain event. For
example—simplifying greatly—if an NPC is attacked,
it would trigger the “combat” script, telling the
NPC to buff up, draw his or her weapon, and charge into battle. There
are many scripts, like scripts that make NPCs fight, eat, patrol, and
many other things.



In order to achieve all of this, we have a huge set of tools that allow
us to configure all of these aspects.



The main tools of concern for AI and scripts:



Scry
– The script editor, this is the tool we use to create
behavior for NPCs and actions of items in the world.

The brain tool
- Configures brains, Maslovian Pyramids and EPTs.

The Monster Tool
- Configures senses and the brain attached to an NPC.

Genesis
– This is our world and gameplay editing software. This is
where NPCs are placed in the world and scripts for items are attached.



Scripts are also responsible for triggering numerous things in the
world. They can listen for an event when a player interacts with a
certain item or enters a certain area, open doors, burn the player if
they touch fire, and even teleport the player from one place to
another. Scripts can be attached to almost all Dynamic Elements of the
game and are also responsible for the core of our Tutorial and
cut-scene system. An often overlooked part of scripting is sound. Age
of Conan offers full surround-sound and this is also configured from
scripts – what sounds are emitted when, how loud they are,
how they travel through the world etc.



In combination, this system gives us one of the most flexible AI
systems of any MMORPG ever. We make use of these technologies to offer
truly deep AI to Age of Conan.