The Effects of Latency on User Performance in Warcraft III

The Effects of Latencyon User Performance in

Warcraft IIINathan Sheldon, Eric Gerard, Seth

Borg, Mark Claypool, Emmanuel AguComputer Science DepartmentWorcester Polytechnic Institute

Worcester, MA, USAhttp://www.cs.wpi.edu/~claypool/papers/war3/

May 2003NetGames'03, Redwood City, CA, USA2

Why Study Network Games?•In 2000, U.S. economy grew by 7% while

computer game industry grew by 15%

•60% of Americans age 6+ play computer games

•221+ million computer games sold in 2002– 2 games for every household in America

“Top Ten Industry Facts”, Interactive Digital Software Association, May 2003.

“Economic Impacts of the Demand for Interactive Entertainment Software”, Interactive Digital Software Association, 2001.


Why Study Warcraft III?

•Top selling computer game genres– Strategy (27.4%)– Children’s (15.9%)– Shooter (11.5%)– Family Entertainment (9.6%)

•Warcraft III set sales record – Fastest to sell 1 million copies

“Warcraft III - Shatters Sales Records Worldwide...”, Blizzard Press Release, October 2002

“Top Ten Industry Facts”, Interactive Digital Software Association, May 2003.


Network Games and Latency• Latency degrades performance of interactive

applications– Web-browsing – seconds– Audioconference – 100’s of milliseconds– First Person Shooters (FPS) – 100’s of milliseconds

•Real-Time Strategy (RTS)? • Knowing effects of latency useful for

– Building better network games– Building better networks to support games (QoS)

Effects of Latency on Warcraft III (RTS)


Outline

•Introduction

•Experiments

•Analysis

•Conclusions


Warcraft III Overview

RTS User Interaction Components:• Exploration• Building• Combat


Exploration Map

Performance?• Time(to reach end)


Building Map

Performance?• Time(to build tech-nology tree)


Combat Map

Performance?• Games Won• Unit Scores


Controlling Latency

•Warcraft III uses client-server– Set computer B as server (also a client)– Set computer C or D as client

•NIST Net on computer A – Induce latency [0 ms to 3500 ms]


Outline

•Introduction

•Experiments

•Analysis– Application Level – Network Level– User Level

•Conclusions


Building and LatencyBuild Time vs. Latency

R2 = 0.0516

7:40

7:55

8:09

8:248:38

8:52

9:07

9:21

9:36

0 500 1000 1500 2000 2500 3000 3500 4000

Latency (ms)

Build

Tim

e (m

:s)

Time To Build Linear (Time To Build)


Exploration and LatencyExplore Time vs Latency

R2 = 0.6334

3:50

4:04

4:19

4:33

4:48

5:02

5:16

5:31

0 200 400 600 800 1000 1200

Latency (ms)

Expl

ore

Tim

e (m

:s)

Time To CompleteLinear (Time To Complete)


Combat and Latency (1)Unit Score Difference vs. Latency

R2 = 0.0138

-3000-2000-1000

0100020003000

0 200 400 600 800 1000 1200 1400 1600Latency (ms)

Uni

t Sco

re D

iffer

ence


Combat and Latency (2)


Outline

•Introduction

•Experiments

•Analysis– Application Level – Network Level – User Level

•Conclusions


Bandwidth

3.8 Kbps

4.0 Kbps

6.8 Kbps


Inter-Packet Times


Payload Distributions


Bandwidth and Latency

•Battle.net games had ~100 ms latency•Trace combat maps with induced

latency


Payload Distributions and Latency


Commands and Latency•Pilot studies suggest 6 bytes of

overhead per command•Remove 6 bytes from each packet

payload•Add up remaining command payloads


Outline•Introduction

•Experiments

•Analysis– Application Level – Network Level – User Level

•Conclusions


User-Level Analysis•0-500 ms latency, users could easily adjust•800+ ms, game appeared erratic

– Degradation in gaming experience•500-800 ms degradation depended upon

– User •More skilled were more sensitive

– Strategy•Micro managers were more sensitive•Combat managers were more sensitive


Conclusions• Typical Internet latencies do not significantly

affect user performance in Warcraft III– Some effect on exploration– No statistical effect on building or combat

• RTS game play emphasizes “strategy” (which takes 10s of seconds or minutes), not “real-time”

• RTS games less sensitive to latency than are FPS– RTS in QoS class similar to that of Web browsing

• At the network level:– Small packets with low bandwidth– Command aggregation at higher latencies


Future Work

•Effects of latency on user strategies•Other RTS games

– Age of Empires– Command and Conquer

•Effects of latency on other genres– First Person Shooter– Role Playing Game

•Effects of loss

The Effects of Latencyon User Performance in

Warcraft IIINathan Sheldon, Eric Gerard, Seth

Borg, Mark Claypool, Emmanuel AguComputer Science DepartmentWorcester Polytechnic Institute

Worcester, MA, USAhttp://www.cs.wpi.edu/~claypool/papers/war3/

The Effects of Latency on User Performance in Warcraft III

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