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The Effects of Latency on Online Madden NFL Football. James Nichols and Mark Claypool Computer Science Department Worcester Polytechnic Institute Massachusetts, USA. NOSSDAV 2004 - Kinsale, County Cork, Ireland. Motivation. Why study network games?
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The Effects of Latency on Online Madden NFL Football James Nichols and Mark Claypool Computer Science Department Worcester Polytechnic Institute Massachusetts, USA NOSSDAV 2004 - Kinsale, County Cork, Ireland
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 NOSSDAV 2004
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% NOSSDAV 2004
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 NOSSDAV 2004
Test environment NOSSDAV 2004
Dumb Client Model NOSSDAV 2004
Client-side prediction NOSSDAV 2004
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 NOSSDAV 2004
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 NOSSDAV 2004
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 NOSSDAV 2004
Symmetrical Latencies NOSSDAV 2004
Asymmetrical Latencies NOSSDAV 2004
Effect of latency on running • First, isolate running • What about NPC interactions? NOSSDAV 2004
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 NOSSDAV 2004
Quantitative Results NOSSDAV 2004
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 NOSSDAV 2004
Example Player is pressing left Player is pressing up Running back goes out of bounds NOSSDAV 2004
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 NOSSDAV 2004
The Effects of Latency on Online Madden NFL Football James Nichols and Mark Claypool http://perform.wpi.edu NOSSDAV 2004 - Kinsale, County Cork, Ireland