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 This Primitive Owlbeast is pumped. – Creatures will generally move straight at the player. – Creatures will move around obstacles and over mountainous terrain. – Terrain that restricts players also restricts creatures. 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 This is where I run away. • Social Behavior – Some creatures will call out for aid if they are attacked. – Less intelligent creatures (like beasts) will not help their comrades. 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 Move along fellas, you don’t want none of this. – Some creatures will patrol a certain path. – Some creatures will wander around a certain area. – Some creatures will just stand around like goons. 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’?