1 The Effects of Latency on Online Madden NFL Football James Nichols and Mark Claypool Computer Science Department Worcester Polytechnic Institute Massachusetts, USA NOSSDAV Kinsale, County Cork, Ireland

2 Motivation Why study network games? In 2003, despite economic downturn, games only industry to grow [ESA ] 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

3 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 % First-Person Shooter % Sports - 6.3% Console Games Strategy - not reported! (small) First-Person Shooter - 5.5% Sports % NOSSDAV 2004

4 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

5 Test environment NOSSDAV 2004

6 Dumb Client Model NOSSDAV 2004

7 Client-side prediction NOSSDAV 2004

8 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

9 Results

10 Results

11 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

12 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

13 Symmetrical Latencies NOSSDAV 2004

14 Asymmetrical Latencies NOSSDAV 2004

15 Asymmetrical Latencies

16 Effect of latency on running First, isolate running What about NPC interactions? NOSSDAV 2004

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18 NOSSDAV 2004

19 Experiment Hypothesize that offensive production (Yards/Attempt) will decrease as latency increases Play 3 full games at 8 different latencies ( ms rtt) One team runs over and over again Other team punts the ball right back NOSSDAV 2004

20 Quantitative Results NOSSDAV 2004

21 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

22 Example Player is pressing leftPlayer is pressing up Running back goes out of bounds NOSSDAV 2004

23 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

24 The Effects of Latency on Online Madden NFL Football James Nichols and Mark Claypool NOSSDAV Kinsale, County Cork, Ireland