This document discusses the evolution of multiplayer games from early single-player games to modern mobile multiplayer games. It outlines four levels of multiplayer interaction: 1) read-only scores, 2) turn-based gameplay with an inbox, 3) real-time interaction, and 4) real-time mobile interaction. Achieving real-time multiplayer gameplay on mobile presented bandwidth, latency, packet loss, and jitter challenges that required experimenting with client prediction, UDP, and sending full state updates to enable playable games over 3G networks. The document concludes by discussing improvements to matchmaking, debugging tools, and opening positions at the company.

1. Reliving the history of
multi player games
@phuesler @rirei

6. At Wooga
Evolution
is driven by teams

7. Technologies

8. Architecture

9. Platforms

10. User interaction

11. Level 1:
Read-only
interaction

12. High score
Pacman

16. read-only access
Client
Score
DB
Client

17. Level 2:
Inbox
interaction

18. Turn based
Empire Civilization

20. inbox
Client
Inbox
Client
DB

21. Inbox interaction
Client
Inbox
App
Client

22. woo.ga/backend

23. Level 3:
Real
interaction

24. Real interaction
MUD World of Warcraft

27. Real interaction
Client
Usr Usr
Loc
App
Client

29. Handling conflicts
Client
Usr Usr
Loc
App
Log Log
Client

31. woo.ga/backend

32. Level 4:
Real time
interaction

33. Real time interaction
Super Mario Kart Starcraft

34. Player 1 Player 2
Server

35. Player 1 Player 2
Server

36. Player 1 Player 2
Server

37. Sources of inspiration

38. • good throughput
• low latency
• low packet loss
• no jitter
We depend on

39. Level 4:
Real time
interaction on mobile

40. 3G
Internet

41. Bandwidth
0.73 Mbps
1.2 Mbps3G
https://de.wikipedia.org/wiki/High_Speed_Uplink_Packet_Access
https://de.wikipedia.org/wiki/High_Speed_Downlink_Packet_Access

42. Added Latency (RTT) *
3G 70 - 180 ms
http://202.194.20.8/proc/VTC09Spring/DATA/09-18-19.PDF
* HSDPA/HSUPA

43. Packet loss

44. Latency Jitter
0
75
150
225
300
RTT ms

45. Let’s do
Bomberman

47. Client Prediction
Extrapolation
Interpolation
Lag Compensation
Latency Object Replication
Quality of Service
Physics
Collision Detection
TCP
UDP
Real Time
Match Making
Packet Loss
Synchronization
Peer-To-Peer
Lockstep
Protocol

49. 1

50. Architecture
C1 C2Server
move :up c1 moved :up
place bombc2 placed bomb
bomb exploded bomb exploded
game over game over

51. TCP
JSON
EASY!!!

52. Works on
Wifi:)

53. game doesn’t
work on 3G
:(

54. Jitter

55. Dropped packets

56. TCP Packet Ordering and
Resend

57. TCP Flow and Congestion
Control

58. Warping
noupdate
noupdate
noupdate
4 updates
at once

59. or
WORSE
:(

60. 2

61. Architecture
move :up
C1 C2Server
c1 moved :up
place bombc2 placed bomb
bomb exploded bomb exploded
game over game over

62. UDP 3G
Will it work?

63. Poor man’s TCP
User Id Local Seq No Remote Seq No Ack bitfield
JSON PayloadJSON PayloadJSON PayloadJSON Payload
• http://gafferongames.com/networking-for-game-programmers/reliability-and-flow-control/

64. Poor man’s TCP
Ordering
Acknowledge Packets
Resending Packets
Flow Control
Congestion Control
✔
✔
X
X
X

65. UDP 3G
✔Tested with a few providers in Germany, Switzerland and Netherlands

66. game barely
works on Wifi
:|

67. game doesn’t
work at all on
3G!!!
:(

68. Packet Loss

69. No synchronization

70. 3

71. UDP
JSON
State updates

72. Send full state
Full State
Full State
Full State
Full State

73. MTU
Ethernet 1500 bytes
PPPoE 1492 bytes
Edge 1440 bytes
https://en.wikipedia.org/wiki/Maximum_transmission_unit
http://ipixcel.org/EDGE_Capabilities,_Technology,_and_Applications_PDF.pdf

74. Architecture
C1 C2Server
move :up
state update state update
state update state update
game over game over
move :down

75. 10 msg/second

76. 100 ms walking speed

77. Game
works on
3G:)

78. Highscores and
Matchmaking are
BROKEN!:(

79. 4

80. Architecture
C1 C2Server
move :up
state update state update
state update state update
game over game over
move :down

81. Different Concerns
Game
Play
Matchmaking
Highscores
Login/Logout
User Data
Reliable Unreliable

82. Different Concerns
Game
Play
Matchmaking
Highscores
Login/Logout
User Data
HTTP UDP

83. Server architecture
Lobby Server
HTTP Service
User Registry
Matchmaking
Logic
Game Server
UDP Service
User Registry
Game Logic
RPC
Database

84. UDP
Binary

85. Binary protocol
64 bit 32bit 32bit 8bit 8bit Rest
User Id SeqNr Ack Bitfield Command Payload
144 bits 944 bits
118 bytes18 bytes

86. 2 Player State update
~
136 bytes

87. 56K Modem
7 KBps
10 msg/second
1.420 KBps
✔

88. Improved
Gameplay
:)

89. 5

90. FIFO with timers

91. Casual Matchmaking
Skill Time
4 Players
Match

92. Hierarchical Clustering

93. Better Matchmaking
1
2
3
4
5
6
7
Queueing
=10
10
10
10
Start Game
1
2
3
4
5
6
7
Find Matches
=1
Reschedule
2
3
4
6
10
10
10
=1

94. Better
Matchmaking:)

95. Geo Matching

96. Play
Locally:)

97. Debugging

98. Terminal Client

99. Bots

100. Network Link Conditioner

101. Erlang tools
erlscript
WX
Widgets
Remote Shell
Hot Code
Reload

102. Level 4:
Finished
mobile multi player

103. User interaction

104. Questions?
@phuesler @jrirei
http://wooga.com/jobs