The document discusses various examples of AI in gaming, including The Sims, Halo, and Black & White from the early 2000s. It notes that since the mid-2000s, game AI has not advanced much beyond a "chest-high wall". Examples of more recent AI systems are discussed for Far Cry 2 and 3 with improvements to animal AI. The Walking Dead game had poor zombie AI that did not properly focus on the player. Left 4 Dead's "AI Director" is praised for dynamically adjusting zombie spawns based on player performance. Examples are also given of effective combat AI in Bully and techniques used for Ellie's AI in The Last of Us.

1. Technical Challenges of Artificial
Intelligence in gaming
An analysis of the use of AI in gaming and the
challenges it presents to developers by Joshua
Matthews.

2. Lets start with some positives: some early examples of great, innovative forms of AI…
• The Sims (2000) – The best selling PC game of all time, The Sims revolutionised
the AI spectrum, placing behavior responsibilities on the actors environment via
Smart Objects, providing a number of basic desires for the Sims to drive their
actions individually and modeling emotional interactions, allowing relationships to
form. Gameplay - https://www.youtube.com/watch?v=e20QY7Hx88s
• Halo (2001) – The first title of this successful franchise brought many innovations.
The enemies use cover wisely and employ suppressive fire and grenades; the
situation of the squad has an impact on its individuals (when team leader dies, team
members flee); plus, there’s a lot of attention to detail. For example, enemies throw
grenades back at the player and team members will respond if the player should
bother them. -
• Black & White (2001) - Published by Lionhead Studios, this god game featured
interacting with a giant AI creature which can learn from examples, and takes
reward and punishment. Its engine uses a solid AI architecture, rooted in cognitive
science, known as belief-desire-intention (BDI) and machine learning techniques
such as decision trees and neural networks are used with great success.

3. The mid 2000’s downfallNotice how all of those games that I just mentioned are at least 12 years old? It is said that
from around the mid-2000s videogame AI nestled itself beneath a “chest-high wall” and has
pretty much stayed there ever since.
Far Cry
The Far Cry series has had a mixed relationship with AI over the course of its last two titles. Being
open world games, this series has more aspects to cover in terms of AI, mainly revolving around its
natural environment. Far Cry 2 had some great ideas for its animal AI. They developed a spawning
technique that allowed them to take advantage of the fact that, in real life, Animals don’t stay in the
same place. This was combined with an encounter system, that spawned various AI in the game
based on what’s already there. However, less predators were actually included within the game
world as the developers couldn’t control their AI and stop them from eating all the herbivores.
Far Cry 3 took a more individual approach to the animals and gave them more detailed virtual
minds. Ubisoft developer Hugo Desmeules explained “So now a turtle brain no longer consists of
only going left and right and being crushed by a plumber, it needs to flee progressing fire,
move away from an incoming vehicle, transition from ground to water navigable areas, walk,
hide, swim, and care about predators like sharks.”
The upgrade and developments in AI between these two games is quite impressive.

4. ZombiesThe Walking Dead: Survival Instinct had the graphics and premise to have what it takes to be a relatively decent
game. After all, isn’t The Walking Dead one of the most, if not the most well known zombie franchise? Well this
little mess of a game certainly died out due to its laughable AI system. The zombies didn’t share the correct focal
point and often were misdirected.
The zombies need to spawn and direct their attention to the player at a frequent enough rate to present a challenge
and this doesn’t happen. If the zombies are even spawning through the bugged up engine, their attention isn’t
focused on the player and sometimes they don’t even approach them. This would’ve been an easy behavior to
imply and I believe the true reason why it wasn’t there was due to a rush of development due to a dangerously fast
approaching release date.
https://www.youtube.com/watch?v=dcDLnaqOeHo
The Left 4 Dead franchise’s “AI Director” is the example that all future zombies games should follow. The
Director is designed to detect the whereabouts of the player and spawn a challenging amount of infected
accordingly. The Director will go through phases, which experienced players might even be able to judge and react
to: Build Up - Upon leaving the safe zone, the Director enters Build Up mode. In this mode, Common and Special
infected will spawn normally, and Mobs will appear regularly; Peak - The Director reaches "Peak" when the
Survivors are at maximum Intensity. It usually occurs at the peak of combat. Infected normally stop spawning at
this point.; Relax - During Relax phase, Survivors may rest and recouperate after passing through Peak phase.;
The Director constantly measures how much pressure each individual Survivor is under by monitoring their
Intensity. A Survivor's Intensity increases when attacked by an Infected, and by killing Infected that are close by.
Survivors will immediately reach maximum Intensity when incapacitated. Survivors will not gain intensity through
friendly fire, or when sniping distant Infected.
https://www.youtube.com/watch?v=Ngw5DUcQAMM

5. Playing with the AI
Over the past few years, many have uploaded videos online, demonstrating how
entertaining the AI knowledge of certain game actors is in events such as combat. By
enforcing some slight modifications, CPU actors can fight others without a player
being involved presenting us with total simulated combat, that relies entirely on the
game’s AI system. Some great examples of effective combat AI that I’ve found are
that of Bully by Rockstar Games (2006), a game set in a school, where each of its
‘cliques’ have their own unique rivalries and fighting styles. Certain actions that the
player does can have an effect on their reputation with that clique. For instance, if the
player eggs the Jock’s gym in alliance with the Nerds, the Jocks will not take kindly
to his next visit. Also, bullying certain individuals will provoke the Prefects to
apprehend you. Anyway, here’s a few videos of modifications that help convey the
different fighting styles and rivalries as a result of the AI.
https://www.youtube.com/watch?v=alHd9UUkZmU
https://www.youtube.com/watch?v=_tIRG8Xa8RM

6. The Last of US
Rays
Rays are technique that Naughty Dog used to avoid a big problem encountered within the
devlopment process of their Buddy AI, that ensured the Ellie was always realistically
reacting to Joels actions against enemies. It had to be restarted a few weeks before release
as they saw too many weaknesses within it.
Ray diagrams were used to show the different points were Ellie could stand in perespective
to Joel. The developers had to analyse these points, remove the points where she would
stand that would either be too close to the enemies or ridicolously out of Joel's sight and
adapt that basic perspective to every instance where they meet a group of enemies,
adapting in a way that doesn't enable it to look too rigid and unrealistic.
Examples of points that would have to be removed include any point where Ellie is faced
directly up against all wall near Joel or if she is standing so curved round to a certain angle
from Joel's perspective, that she is nearer to the enemies than him.
http://www.gdcvault.com/play/1020364/Ellie-Buddy-AI-in-The
In the above presentation,