CIS 588 AI Evaluation for World of Warcraft Jonathan Schmoll February 14, 2005

About World of Warcraft Henceforth referred to as “WOW” –Created by Blizzard Entertainment –Release November 23, 2004 –Currently the #1 game in its genre WOW is a MMORPG: –Massively Multiplayer Online Role Playing Game

Artificial Intelligence in WOW Used to control (mainly) enemy NPCs Used in almost all enemy functions –Movement –Attacking –Social Behavior Some scripting used for special encounters

WOW’s AI Implementation ~ or: Blizzard Doesn’t Care That I’m a Grad Student Doing a Presentation On AI Uses a strongly rules-based approach –Apparently based on expert systems –Special scripting does not break AI rules –Possibly uses Lua scripting language Blizzard did not want to divulge their secrets –Info based on obtuse contact with Blizzard, Internet research, and a lot of forum trolling.

AI Behavior Study The following slides detail the adventures of Johnny the Human Priest during his study of WOW’s creature behavior.

AI Behavior Study Terrain Navigation –Creatures will generally move straight at the player. –Creatures will move around obstacles and over mountainous terrain. –Terrain that restricts players also restricts creatures. This Primitive Owlbeast is pumped.

AI Behavior Study Terrain Navigation (cont.) –Some creatures will not follow you into water. Now who’s tough, Mr. Can’t Swim.

AI Behavior Study Creature Aggression –If a creature knows it can kill you, it will go out of its way to attack you. –Simulates how much a creature “fears” a player. Obviously this dragon isn’t too afraid of me.

AI Behavior Study Creature Aggression (cont.) –Weaker creatures will not attack until the player is very close. –Some creatures will regard the player as neutral. –Some creatures will attack other creatures. This is why you don’t leave your chickens out.

AI Behavior Study Social Behavior –Some creatures will call out for aid if they are attacked. –Less intelligent creatures (like beasts) will not help their comrades. This is where I run away.

AI Behavior Study Fleeing –More intelligent “humanoid” creatures will attempt to run when they are about to die. –Beasts will fight to the death. This is bear is going down. Hard.

AI Behavior Study Movement –Some creatures will patrol a certain path. –Some creatures will wander around a certain area. –Some creatures will just stand around like goons. Move along fellas, you don’t want none of this.

AI Behavior Study Attack Range –Ranged attackers will attempt to keep their distance. –Melee attackers will get right up in your face. This troll didn’t appreciate my Jolly Green Giant jokes.

AI Behavior Study Special Abilities –Some creatures have special abilities and will use them during battle (for example, healers will heal their comrades and themselves.) Whitemane revives her buddy while my party members take a nap.

AI Strengths & Weaknesses Strengths –Relatively Bug-free –Doesn’t feel “cheap” –Works well for the MMORPG genre –Is difficult to exploit –Is predictable Weaknesses –Doesn’t “learn” –Has limited options –Is predictable

AI’s Effect On Gameplay Creatures first appear very smart –This lends itself very well to the “small player in a big world filled with monsters” adventure aesthetic. The AI is fairly transparent –This sounds like a bad thing, but it isn’t. As your character “grows”, so does your understanding of creature behavior.

AI’s Effect On Gameplay (cont.) The gameplay changes as you level up. –Since high level players have seen most of the game world, the adventure aesthetic becomes less important. –Game play becomes more strategic. –Creatures are extremely powerful at high levels. Unpredictable behavior would be frustrating when there is a penalty for dying and there is no “reload” option WOW’s persistent game world.

AI’s Effect On Gameplay (cont.) Scripting adds flavor –Scripted creature behavior inside special dungeons adds a controlled unpredictability to the game. Players are forced to quickly come up with solutions to these “puzzles”. –Scripted events still work within the creature’s AI rules (for example, a healer will not suddenly begin performing warrior abilities.)

Questions / Comments ? Who doesn’t like a little gnome-on-human dancin’?