This document provides an introduction to the CS4344 lecture on technical issues and solutions in networked and mobile game development. It outlines the course objectives, assessment breakdown, workload, and additional resources. The lecture then discusses key concepts like networked games, multiplayer game architectures, and the challenges of building consistent, responsive, fair, and scalable networked games over best-effort networks.

1. Lecture 1
Introduction to CS4344
11 January 2010
1

2. Ooi Wei Tsang
AS6 05-14
ooiwt@comp.nus.edu.sg
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3. About CS4344
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4. • To learn about technical issues and
solutions in networked/mobile
game development
• Complements CS4213 “Game
Development”
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5. 2 Hour Lecture
10am - 12noon
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6. We are at the frontier of
the topic
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7. No perfect textbook for
this class. But we will use
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8. SGD 180
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9. SGD 160
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10. 10

11. Additional materials comes
from online resources and
research papers.
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12. So, don’t swallow everything
you read (and I say) without
thinking.
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13. CS4344 Assessment
Final Exam Assignments Quizzes/Midterm
25%
35%
40%
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14. CS4344 Workload/Week (hours)
Lecture Prepare Homework
2
6
2
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15. More info about
assignments coming soon
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16. http://blog.nus.edu.sg/cs4344/
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17. Student Feedback
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18. Overall Opinion
4
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19. Likely Grade
4.2
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20. Difficulty
3.7
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21. Questions?
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22. “Networked Games” ?
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23. Games that involve more
than one hosts
communicating over the
network
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24. 24

25. Games that involve more
than one player
communicating over the
Internet/LAN
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26. Turn-based Multi-player Games
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27. Real-time Multi-player Games
http://www.gameslander.com/world-of-warcraft-game-review-94.phtml
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28. We focus on real-time
multi-player games in
CS4344
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29. MMORPG
http://www.gameslander.com/world-of-warcraft-game-review-94.phtml
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30. First Person Shooter
http://playstation3.files.wordpress.com/2005/12/Unreal-tournament-2007-screenshot4.jpg
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31. Real-time Strategy Game
http://www.auran.com/games/images/frontline_fields_of_thunder/screenshots/large1.jpg
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32. We focus on real-time
multi-player games in
CS4344
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33. and other similar
applications
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34. Military Training Simulator
http://www.defenselink.mil/transformation/images/photos/photo_archive/index_2005-05.html
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35. Networked Virtual Environment
http://www.archiveshub.ac.uk/blog/2007_04_01_archiveshubblog_archive.html
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36. interactive,
distributed simulations
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37. An Abstract Model for
Networked Games
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38. A generic loop for games
Collect Events
Simulate Game
Render
Wait
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39. A generic loop for games
Collect Events
events
Game
Simulate Game
States
states
Render
Wait
39

40. Can be viewed as a sequence of states that
changes over time, in reaction to events.
Time
States
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41. A state can be discrete or continuous.
Time
State changes over time
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42. Example events: user input, timer, messages
from other hosts.
Time
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43. A host may send messages to other hosts.
Message can be state or event.
Time
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44. Example: Two-player Pong
States: position of peddles and ball
Events: movement
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45. A moves peddle Ball hits peddle
Player A
Player B
B moves peddle
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46. Basic
Communication
Architectures
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47. Centralized Architecture
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48. Client sends events to the server. Server
computes new states and updates clients with
new states.
Player A
Server
Player B
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49. Client sends events to the server. Server
computes new states and updates clients with
new states.
Player A
Server
Player B
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50. states
Simulate Collect Events
events
Game
Game
or States
Game Render
States
Wait
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51. “Smart” server, dumb clients
Role of server
Maintain states
Simulate games
Notify clients
Resolve conflicts
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52. Dumb server, smart clients
Role of server
Notify clients
Resolve conflicts
Role of clients
Maintain states
Simulate games
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53. Clients simulate and maintain states. Server
resolves conflicts and forwards events to
clients.
Player A
Server
Player B
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54. Collect Events
events
Game
Simulate Game
States
Server states
Render
Wait
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55. Point-to-Point Architecture
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56. Point-to-Point Architecture
Role of clients
Notify clients
Resolve conflicts
Maintain states
Simulate games
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57. Clients simulate the game, maintain states, and
forward message to each other.
Player A
Player B
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58. Collect Collect
Game Simulate Game
Simulate
States States
Render Render
Wait Wait
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59. Maintaining consistency is not trivial.
Player A
Player B
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60. Centralized vs. Distributed
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61. Design Requirements
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62. Responsive
(reacts to player’s action)
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63. Consistent
(players have the same view of
the game state)
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64. Cheat Proof
(player cannot cheat)
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65. Fair
(should be fair to all players)
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66. Resource Efficient
(minimal amount of network
traffic, CPU cycles, memory)
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67. Scalable
(able to handle large number
of players)
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68. Robust
(able to handle failure
gracefully)
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69. Simple
(easy to implement/maintain)
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70. Why Difficult?
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71. Internet is a
best-effort network
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72. Packets take time to travel.
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73. Packets can be dropped or corrupted
X
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74. Ideally, updates should reach other players immediately,
so that states are consistent at all time.
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75. Delay and loss lead to inconsistent states.
X
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76. number of players
can be huge
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77. 77

78. 78

79. 79

80. Huge cost in network/CPU resources
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81. players are competitive
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82. Players cheat to gain advantage
http://www.msxsecurity.com/bbf21421.jpg
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83. games should be
fair to all players
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84. network delay and losses
large number of users
cheating
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85. Latency
Robustness
Conflict/Cheating
Consistency
Accounting
Scalability
Complexity
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