web.cs.wpi.edu

1

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
2
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
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 - 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
4
Latency and Network Games

• Effects of latency on interactive network
  applications well studied
• Web-browsing seconds
• Audio conference 100s of milliseconds
• Games are highly interactive!
• First-person shooters 100s of ms
• Real-time strategy games
• What about sports?
• EA Sports 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 Alphas 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 Betas 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
17
(No Transcript)
18
NOSSDAV 2004
19
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
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 left
Player 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 dont 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 http//perform.wp
i.edu
NOSSDAV 2004 - Kinsale, County Cork, Ireland