Mimicking human player strategies in ghting games using game arti cial intelligence techniques

144 Pages·2017·2.14 MB·English

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Mimicking human player
strategies in fighting games
using game artificial
intelligence techniques
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Additional Information:
• A Doctoral Thesis. Submitted in partial fulfilment of the requirements
for the award of Doctor of Philosophy of Loughborough University.
Metadata Record: https://dspace.lboro.ac.uk/2134/16380
Publisher: (cid:13)c Simardeep Singh Saini
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Please cite the published version.
Mimicking Human Player Strategies in Fighting
Games Using Game Artificial Intelligence
Techniques

By
Simardeep Singh Saini

A Doctoral Thesis
Submitted in partial fulfilment of the requirements for the award of
Doctor of Philosophy of Loughborough University

March 2014

© By Simardeep Singh Saini 2014
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Abstract
Fighting videogames (also known as fighting games) are ever growing in popularity and accessibility.
The isolated console experiences of 20th century gaming has been replaced by online gaming services
that allow gamers to play from almost anywhere in the world with one another. This gives rise to
competitive gaming on a global scale enabling them to experience fresh play styles and challenges by
playing someone new.
Fighting games can typically be played either as a single player experience, or against another human
player, whether it is via a network or a traditional multiplayer experience. However, there are two
issues with these approaches. First, the single player offering in many fighting games is regarded as
being simplistic in design, making the moves by the computer predictable. Secondly, while playing
against other human players can be more varied and challenging, this may not always be achievable
due to the logistics involved in setting up such a bout. Game Artificial Intelligence could provide a
solution to both of these issues, allowing a human player’s strategy to be learned and then mimicked
by the AI fighter.
In this thesis, game AI techniques have been researched to provide a means of mimicking human
player strategies in strategic fighting games with multiple parameters. Various techniques and their
current usages are surveyed, informing the design of two separate solutions to this problem. The first
solution relies solely on leveraging k nearest neighbour classification to identify which move should
be executed based on the in-game parameters, resulting in decisions being made at the operational
level and being fed from the bottom-up to the strategic level. The second solution utilises a number
of existing Artificial Intelligence techniques, including data driven finite state machines, hierarchical
clustering and k nearest neighbour classification, in an architecture that makes decisions at the
strategic level and feeds them from the top-down to the operational level, resulting in the execution
of moves. This design is underpinned by a novel algorithm to aid the mimicking process, which is used
to identify patterns and strategies within data collated during bouts between two human players. Both
solutions are evaluated quantitatively and qualitatively. A conclusion summarising the findings, as well
as future work, is provided. The conclusions highlight the fact that both solutions are proficient in
mimicking human strategies, but each has its own strengths depending on the type of strategy played
out by the human. More structured, methodical strategies are better mimicked by the data driven
finite state machine hybrid architecture, whereas the k nearest neighbour approach is better suited
to tactical approaches, or even random ‘button bashing’ that does not always conform to a pre-
defined strategy.
Keywords: Fighting Games, Artificial Intelligence, Finite State Machine, Machine Learning, Game AI,
Strategies and Tactics, Mimicking
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Acknowledgements
I would like to thank my supervisors Professor Paul Chung and Dr Christian Dawson for their continued
support, guidance and mentoring during my research. I would also like to extend my gratitude to Dr
Daniel Reidenbach, whose feedback has been of utmost importance in shaping this Thesis.
I am eternally grateful to my mother and father, my brother Amardeep, and my sister-in-law Sarbjit,
for believing in me and telling me to never give up. The completion of this work would not have been
possible without their undying support, encouragement and patience.
I am indebted to those managers I have worked for over the years who have supported my studies by
offering time off work to pursue my research. This has made a big difference and I am grateful for all
they have done.
Last, but certainly not least, I would like to thank my friends and family all over the world who have
helped me along the way, and whose understanding and patience has been paramount to progressing
the doctorate. Many thanks to Jag and Ricky in particular for their constant backing and
encouragement over the years.
Above all, I would like to thank God Almighty, without whom this achievement would simply not be
possible.

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To My Parents

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Table of Contents

Abstract ................................................................................................................................................... 2
Acknowledgements ................................................................................................................................. 3
Table of Contents .................................................................................................................................... 5
List of Figures .......................................................................................................................................... 8
List of Tables ........................................................................................................................................... 9
Part I – Introduction and Background ................................................................................................... 10
Chapter 1 – Overview ........................................................................................................................... 11
1.1 Introduction ................................................................................................................................ 11
1.2 Motivation ................................................................................................................................... 11
1.3 Research Aims and Objectives .................................................................................................... 12
1.4 Contribution of the Thesis .......................................................................................................... 12
1.5 Structure of the Thesis ................................................................................................................ 14
Chapter 2 – Anatomy of a Fighting Game ............................................................................................. 15
2.1 Introduction ................................................................................................................................ 15
2.2 What is a Fighting Game? ........................................................................................................... 15
2.3 A Brief History of Fighting Games ............................................................................................... 17
2.4 Chapter Summary ....................................................................................................................... 22
Chapter 3 - Strategies and Tactics......................................................................................................... 23
3.1 Introduction ................................................................................................................................ 23
3.2 Strategies and Tactics in Martial Arts ......................................................................................... 23
3.3 Martial Arts Movies ..................................................................................................................... 26
3.4 Strategies and Tactics in Videogames ......................................................................................... 28
3.5 Chapter Summary ....................................................................................................................... 30
Chapter 4 – AI Techniques applied to Fighting Games ......................................................................... 31
4.1 Introduction ................................................................................................................................ 31
4.2 The role of AI in Videogames ...................................................................................................... 31
4.3 Game AI Techniques ................................................................................................................... 33
4.4 Application of Game AI Techniques ............................................................................................ 42
4.5 Fighting Games ........................................................................................................................... 54
4.5 Chapter Summary ....................................................................................................................... 64
Part II – Analysis, Design and Development ......................................................................................... 71
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Chapter 5 – Proof of Concept Game ..................................................................................................... 72
5.1 Introduction ................................................................................................................................ 72
5.2 Design .......................................................................................................................................... 72
5.3 Implementation .......................................................................................................................... 76
5.4 Usage of PoC Game ..................................................................................................................... 78
5.5 Chapter Summary ....................................................................................................................... 80
Chapter 6 – K Nearest Neighbour Solution Architecture and Design ................................................... 81
6.1 Introduction ................................................................................................................................ 81
6.2 System Architecture .................................................................................................................... 81
6.3 Chapter Summary ....................................................................................................................... 87
Chapter 7 –Data Driven Finite State Machine Solution Design ............................................................ 88
7.1 Introduction ................................................................................................................................ 88
7.2 System Architecture .................................................................................................................... 89
7.3 Operational Data Capture ........................................................................................................... 91
7.4 Generating the Tactical Level ...................................................................................................... 92
7.5 Strategic Level ............................................................................................................................. 96
7.6 Execution ..................................................................................................................................... 97
7.7 Design Justification ................................................................................................................... 100
7.8 Chapter Summary ..................................................................................................................... 104
Part III – Evaluation and Conclusion ................................................................................................... 106
Chapter 8 - Evaluation......................................................................................................................... 107
8.1 Introduction .............................................................................................................................. 107
8.2 Experiment Design .................................................................................................................... 107
8.3 Experiment Results ................................................................................................................... 115
8.4 Chapter Summary ..................................................................................................................... 120
Chapter 9 – Conclusion and Future Work ........................................................................................... 122
9.1 Introduction .............................................................................................................................. 122
9.2 Thesis Review ............................................................................................................................ 122
9.3 Summary of Contributions ........................................................................................................ 123
9.4 Limitations and Future Work .................................................................................................... 124
9.5 Thesis Summary and Final Conclusion ...................................................................................... 126
References .......................................................................................................................................... 127
Appendix A.1 – Move List ................................................................................................................... 137
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Appendix A.2 – Sample Human Transcript ......................................................................................... 138
Appendix A.3 – Sample DD FSM Transcript ........................................................................................ 140
Appendix A.4 – Sample KNN Transcript .............................................................................................. 142

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List of Figures
Figure 2.1 – Super Street Fighter 2 Turbo Screenshot .......................................................................... 18
Figure 2.2 – Battle Arena Toshinden Screenshot .................................................................................. 20
Figure 2.3 – Ultra Street Fighter IV Screenshot .................................................................................... 20
Figure 2.4 – Tekken 4 Screenshot ......................................................................................................... 21
Figure 4.1 – A Multilayer Artificial Neural Network .............................................................................. 36
Figure 5.1 – Screenshot of Proof of Concept Game.............................................................................. 77
Figure 6.1 – Data Flow for KNN Solution .............................................................................................. 84
Figure 7.1 – Data flow for DD FSM Solution ......................................................................................... 90
Figure 7.2 – DD FSM Solution Architecture .......................................................................................... 91
Figure 7.3 – Execution of DD FSM Solution .......................................................................................... 99
Figure 8.1 – Observer Perception of DD FSM Performance ............................................................... 117
Figure 8.2 – Observer Perception of KNN Performance ..................................................................... 117
Figure 8.3 – Observer Perception of Both Solutions Combined ......................................................... 118

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List of Tables
Table 4.1 – Literature Review Summary ............................................................................................... 65
Table 5.1 – Proof of Concept game moves ........................................................................................... 75
Table 6.1 – Sample of data spooled from human vs. human ............................................................... 83
Table 6.2 – Human Bout Transcript ...................................................................................................... 86
Table 7.1 – Vector Calculation ............................................................................................................. 93
Table 7.2 – Like State Transitions ......................................................................................................... 97
Table 7.3 – Strategy for Human vs. Human Bout ................................................................................ 101
Table 7.4 – Generated States .............................................................................................................. 102
Table 7.5 – Data Driven Finite State Machine .................................................................................... 102
Table 7.6 – Realtime Data Snapshots ................................................................................................. 103
Table 8.1 – DD FSM Solution Transcript ............................................................................................. 109
Table 8.2 – KNN Solution Transcript ................................................................................................... 110
Table 8.3 – Human Strategies Outline ................................................................................................ 113
Table 8.4 – Data Driven Finite State Machines ................................................................................... 114
Table 8.5 – Observations .................................................................................................................... 116
Table A.1 – Move Representation ...................................................................................................... 137
Table A.2 – Sample Human Transcript ................................................................................................ 138
Table A.3 – Sample DD FSM Transcript ............................................................................................... 140
Table A.4 – Sample KNN Transcript .................................................................................................... 142

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