the effects of latency on online madden nfl football

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The Effects of Latency on Online Madden NFL Football

James Nichols and Mark Claypool

Computer Science DepartmentWorcester Polytechnic Institute

Massachusetts, USA

NOSSDAV 2004 - Kinsale, County Cork, Ireland

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Motivation

• Why study network games?• In 2003, despite economic downturn,

games only industry to grow [ESA - 2004] • 400,000 of the 1.3 million PS2 owners

that bought SOCOM play online regularly [EGM - 10/03]

• Demanding application in terms of network requirements

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Motivation

• Why study sports games?• No one has yet…• Are there different user or network level

requirements for sports games?• Top selling genres in 2002 [“Essential Facts About the

Computer and Video game Industry”, The Entertainment Software Association, 2003]• Computer Games

• Strategy - 27.4%• First-Person Shooter - 11.5%• Sports - 6.3%

• Console Games• Strategy - not reported! (small)• First-Person Shooter - 5.5%• Sports - 19.5%

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Latency and Network Games

• Effects of latency on interactive network applications well studied• Web-browsing: seconds• Audio conference: 100’s of milliseconds

• Games are highly interactive!• First-person shooters: 100’s of ms• Real-time strategy games• What about sports?• EA Sport’s Madden NFL Football Series

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Test environment

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Dumb Client Model

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Client-side prediction

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Simple Experiments

• Experiment 1• Hypothesize that online Madden Football uses

client-side prediction to compensate for lag• Large induced delay from Beta to Alpha

(1500ms)• Alpha on offense• Alpha puts man in motion• Results:

• Beta sees player move on his local display first!• Player on Alpha’s display is lagged

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Results

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Results

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Another experiment

• Experiment 2• Hypothesize that online Madden

Football uses dumb-client model• Large induced delay from Alpha to Beta

(1500ms)• Results:

• Alpha sees player move on his local display first!

• Player on Beta’s display is lagged

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One more simple experiment

• Experiment 3• Hypothesize that symmetrical delay results in

roughly synchronized presentation• Large induced delay in both directions

(1000ms each way)• Results:

• Player movements are delayed on both displays, but are synchronized

• Now we can suggest a lag compensation model for online Madden Football

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Symmetrical Latencies

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Asymmetrical Latencies

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Asymmetrical Latencies

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Effect of latency on running

• First, isolate running• What about NPC interactions?

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Experiment

• Hypothesize that offensive production (Yards/Attempt) will decrease as latency increases

• Play 3 full games at 8 different latencies (0-2000 ms rtt)

• One team runs over and over again• Other team punts the ball right back

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Quantitative Results

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Qualitative Results

• At higher latency, player movements are lagged momentarily behind user input

• Hard to get a feel for the timing of when to spin, juke, stiff-arm, etc.

• Make “mistakes” at high latencies• Run into defender• Run out of bounds

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Example

Player is pressing left Player is pressing up

Running back goes out of bounds

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Conclusions

• Experiments suggest that Madden uses a prediction of round-trip time to delay user input to compensate for latency

• Latency does effect user performance• About 30% of the range we evaluated• Typical latencies don’t have an effect• Future work is to evaluate the effects of

packet loss and investigate other sports games

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The Effects of Latency on Online Madden NFL Football

James Nichols and Mark Claypool

http://perform.wpi.edu

NOSSDAV 2004 - Kinsale, County Cork, Ireland