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