Artificial Intelligence in Game Design

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Artificial Intelligence in Game Design

• Problems and Goals

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AI vs. Gaming AI

• Standard Artificial Intelligence
• Expert Systems
• Probabilistic/Fuzzy Logic
• Robotics
• Machine Learning
• Goal Mencari solusi terbaik dari beberapa
  permasalahan
• Characteristics
• Mahal dan memakan waktu untuk membangun
• Siklus Pemrosesan sangat besar (Large number of
  processing cycles to run)

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AI vs. Gaming AI

• Example Chess (Deep Blue, IBM)
• Pendekatan dasar (MINMAX algorithm)
• Bangun tree kemungkinan langkah n berikutnya.
• Berikan tingkatan masing tree sesuai heuristik
  tertentu
• Pilih langkah berikutnya yg terbaik
• Dikombinasikan dgn pengetahuan heuristik
• Databases of opening moves, endgames
• Hasil
• Bermain pada tingkat kesulitan tinggi (solusi
  terbaik)
• Membutuhkan beberapa menit utk menentukan langkah
  (ok in chess)
• Not viable as commercial chess game!

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Goals of Gaming AI

• Menantang tapi dapat dikalahkan
• Intelligence level artificially limited
• Example number of moves lookahead in chess
• AI not given all information
• Example fog of war in Civilization
• Intelligence level can be set by user
• Possibly learned (Madden 09)
• Problem is often making AI intelligent enough!
• Players will find and take advantage of
  limitations
• Cheats often used to compensate for bad AI

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Example of Gaming AI
Soldier NPC setting up ambush What to hide behind?
Player coming from unknown direction
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Example of Gaming AI

• Memilih secara acak?
• Does not appear intelligent
• Tahu lokasi player sekarang?
• Should not know this (cheat!)
• Berdasar kriteria realistik
• Terrain around soldier
• Past player actions, etc.
• This is most difficult approach!

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Goals of Gaming AI

• Efisiensi
• Harus memakan sedikit siklus prosesor
• Competing with graphics!
• Harus selalu beraksi pada waktu nyata (real time)
• Football, racing, etc.
• Pendekatan sederhana biasanya selalu yang
  terbaik.
• If necessary, may need to tweak game to support
  AI

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Example of Simplification

• Pac-Man
• Ghosts pursue players through maze
• Simple algorithm just move towards player
• Problem ghosts stuck in cul-de-sacs

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Example of Simplification
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Believable NPCs

• Musuh yang menawarkan tantangan
• Orc characters should move realistically
• Boss characters should appear as intelligent as
  player
• Minions yg membutuhkan sedikit pengelolaan
• Example scouts, workers, etc. in Civilization 4
• Frustrating if minions make too many mistakes
• Karakter lain yang tertarik utk berinteraksi
• Example Sims

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Believable NPCs

• Intelligent Action (Aksi Cerdas)
• Pengambilan keputusan yang baik
• Pergerakan yang nyata (realistic)
• Evasion/pursuit of player
• Choosing paths through complex terrain
• Cooperation among group
• Menyimpan aksi sebelumnya (and possibly to
  improve)
• Mencapai tujuan

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Believable NPCs

• Believable as Characters
• Acts like human (or orc, dog, etc.)
• Memiliki keadaan emosional (emotional states)
  yang sesuai
• Based on character, current state
• Tidak selalu mudah ditebak (predictably)
• Crucial to replayablity
• Cannot appear too random
• Dapat berinteraksi dengan player
• Verbal and non-verbal interaction

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Role of Traditional AI

• Good decision making
• Realistic movement
• Evasion/pursuit of player
• Choosing paths through complex terrain
• Cooperation among groups
• Memory of previous actions
• Achieving goals

Decision Trees Finite State Machines
Robotics
Swarm Intelligence
Simple Iterative Learning
Goal-based Planning
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Role of Traditional AI

• Acts like human (or orc, dog, etc.)
• Has appropriate emotional states
• Based on character, current state
• Does not always behave predictably
• Can interact with player
• Verbal and non-verbal interaction

Finite State Machines Probabilistic State
Machines Fuzzy State Machines
Natural Language Parsing
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Role of Traditional AI

• Penyederhanaan umum NPCs dibatasi domain
  tertentu (limited domain)
• Contoh shopkeeper NPC
• Dapat berinteraksi dengan player hanya pada
  domain toko.
• Will not leave shop
• Only understands items for sale in shop
• Only actions are transactions related to items

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Question?