Introduction to AI Role Playing Game (RPG)

Agenda History Types of RPGs AI in RPGs Common AI elements AI techniques RPG Making tool: RPG Maker XP RPG AI Improvement

What is AI? Artificial Intelligence –“the science and engineering of making intelligent machines” –Refer to intelligence as exhibited by an artificial (man- made, non-natural, manufactured) entity Research in AI is concerned with producing machines to automate tasks requiring intelligent behavior. Examples include control, planning and scheduling, the ability to answer diagnostic and consumer questions, handwriting, natural language, speech and facial recognition.

What is RPG? A role-playing game (RPG, often roleplaying game) is a type of game in which the participants assume the roles of fictional characters and collaboratively create or follow stories. Example: –Final Fantasy, Diablo, The Elder Scrolls IV, etc.

History Text based RPGs –Computer RPGs The first commercially available role-playing game: Dungeons & Dragons AI: controlled the enemy final attack decision Graphical RPGs –Console RPGs Real-time combat based because more action- oriented input controllers

Text based RPG NetHack

Action RPG An action role-playing game or Action RPG is a type of computer and console role-playing game which requires quick action or reflexes from the player. So- called "Diablo clones" are also part of this genre. –Ex. Diablo, Dungeon Siege, etc.

Action RPG

Turn-based RPG

MMORPG –Massively Multiplayer Online Role-Playing Game (MMORPG) is a genre of online computer role-playing games (RPGs) in which a large number of players interact with one another in a virtual world. –distinguished from single-player or small multi-player RPGs number of players game's persistent world –Ex. Neverwinter Nights, World of Warcraft

AI in RPGs RPGs are fairly AI intensive –Varying types of gameplay Puzzles, combat, crafting, types of travel etc. –Many hours of game experience ~20-40 hours of gameplay for home computer ~40 hours of gameplay for Console

Common AI elements Enemies An almost endless supply for the player Provide level points, money, items –Behavior patterns Statistical AI (monsters’ database) Complex behavior patterns –Running away –Healing themselves –Fighting in groups

Common AI elements Bosses Monster leaders Increased life point, skill, power, brain Bosses are usually heavily scripted The AI needs to include use of the dialogue system for the game

Common AI elements Nonplayer Characters (NPCs) Computer player in the game that the human player can interact with in ways other than combat Provide information or story advancement –Grammar systems Not very intelligent

Common AI elements Shopkeepers Special NPCs who do business with the player Have extended interfaces Have a notion about the player attitude that affects the shopkeepers dialogue, prices, and items.

Common AI elements Party Members Members of the player’s adventuring party (special NPCs) Simple AI on Party members but allow the player to customize the scripting system Use pathfinding in real time combat

AI techniques Scripting –Computer programming languages that are typically interpreted and can be typed directly from a keyboard. –Common technique to improve the AI system without hiring more programmers Programs are converted permanently into binary executable files Scripts remain in their original form and are interpreted command-by-command each time they are run.

AI techniques Scripting –Most RPGs are linear (objectives of the game must be completed in a fixed sequence) or at most branching linear –In game, Dialogue Flow Stage Direction Game event flags NPC behavior AI Logic

AI techniques Scripting Pros: Save time and increase productivity Increase creativity Provide extensibility Cons: Require scripting learning time Scripted code slower than binary

Scripting IF //If my nearest enemy is not within 3 !Range(NearestEnemyOf(Myself),3) //and is within 8 Range(NearestEnemyOf(Myself),8) THEN //1/3 of the time RESPONSE #40 //Equip my best melee weapon EquipMostDamagingMelee() //and attack my nearest enemy, checking every 60 ticks to make sure he is still the nearest AttackReevaluate(NearestEnemyOf(Myself),60) // 2/3 of the time RESPONSE #80 //Equip a ranged weapon EquipRanged()//and attack my nearest enemy, checking every 30 ticks to make sure he is still the nearest AttackReevaluate(NearestEnemyOf(Myself),30) END /* Sample Warrior AI User Defined Script from Baldur’s Gate (AI Game Engine Programming) */

AI techniques Finite-State Machine (FSMs) –Split the game into explicit states

FSM

AI techniques Messaging –Messaging system –Parse information between party members, facilitate group combat or dialogue

Messaging Combat World Living World

RPG Maker XP RPG game making tool XP version includes Scripting function Ruby Game Scripting System (RGSS)

RPG Maker XP

RPG Maker XP Demonstration

RPG’s AI Improvement AI Storyteller –A series of events with multiple variables, and a "pacing manager" that ensures the story remains interesting throughout the game. Create dynamic game story to satisfy the player Ex. Dramatic story, happy ending, etc.

RPG’s AI Improvement Fully Realized Towns –Breathing town would make the game world much more interesting and immersive

RPG’s AI Improvement Human-like NPCs (NPCs with memory) –More intelligent NPCs reacting with the situations in RPG world –Have daily routines (life cycle) –Use need-base system with need pathfinding –Ex. Zelda, Utima V, Obivion, etc.

RPG’s AI Improvement Enemies with better combat tactics Baiting the player “Stepping-stone” pathfinding Fighting in groups

RPG’s AI Improvement Role-playing Does Not Equal Combat –Creating content or quests doesn’t involve killing for nonlethal classes Ex. Harvest Moon: –to plant seeds to grow fruits and vegetables in different seasons –to balance the character physical resources

RPG’s AI Improvement Grammar Machines (GMs) –Better conversation engines –Dynamic NPCs text responding –Utilize speech recognition software –Allow the user to really ask questions Ex. –Utima: keyword system

RPG’s AI Improvement Quest Generators –More varied and long lasting gameplay situation –Generate quests according to the players interest –Use ad-lib system to generate unique quests or add new content

RPG’s AI Improvement Better Party Member AI –The character can keep track of the often player actions when fighting and using items –Learning by imitation –Party members script editor