The Effects of Latency on User Performance in Warcraft III

1. The Effects of Latencyon User Performance in Warcraft III Nathan Sheldon, Eric Gerard, Seth Borg, Mark Claypool, Emmanuel Agu Computer Science Department Worcester Polytechnic Institute Worcester, MA, USA http://www.cs.wpi.edu/~claypool/papers/war3/

2. Why Study Network Games? • In 2000, U.S. economy grew by 7% while computer game industry grew by 15% • 60% of Americans age 6+ play computer games • 221+ million computer games sold in 2002 • 2 games for every household in America “Economic Impacts of the Demand for Interactive Entertainment Software”, Interactive Digital Software Association, 2001. “Top Ten Industry Facts”, Interactive Digital Software Association, May 2003. NetGames'03, Redwood City, CA, USA

3. Why Study Warcraft III? • Top selling computer game genres • Strategy (27.4%) • Children’s (15.9%) • Shooter (11.5%) • Family Entertainment (9.6%) • Warcraft III set sales record • Fastest to sell 1 million copies “Top Ten Industry Facts”, Interactive Digital Software Association, May 2003. “Warcraft III - Shatters Sales Records Worldwide...”, Blizzard Press Release, October 2002 NetGames'03, Redwood City, CA, USA

4. Network Games and Latency • Latency degrades performance of interactive applications • Web-browsing – seconds • Audioconference – 100’s of milliseconds • First Person Shooters (FPS) – 100’s of milliseconds • Real-Time Strategy (RTS)? • Knowing effects of latency useful for • Building better network games • Building better networks to support games (QoS)  Effects of Latency on Warcraft III (RTS) NetGames'03, Redwood City, CA, USA

5. Outline • Introduction  • Experiments  • Analysis • Conclusions NetGames'03, Redwood City, CA, USA

6. Warcraft III Overview • RTS User Interaction • Components: • Exploration • Building • Combat NetGames'03, Redwood City, CA, USA

7. Exploration Map • Performance? • Time • (to reach end) NetGames'03, Redwood City, CA, USA

8. Building Map • Performance? • Time • (to build tech- • nology tree) NetGames'03, Redwood City, CA, USA

9. Combat Map • Performance? • Games Won • Unit Scores NetGames'03, Redwood City, CA, USA

10. Controlling Latency • Warcraft III uses client-server • Set computer B as server (also a client) • Set computer C or D as client • NIST Net on computer A • Induce latency [0 ms to 3500 ms] NetGames'03, Redwood City, CA, USA

11. Outline • Introduction  • Experiments  • Analysis • Application Level • Network Level • User Level • Conclusions NetGames'03, Redwood City, CA, USA

12. Building and Latency NetGames'03, Redwood City, CA, USA

13. Exploration and Latency NetGames'03, Redwood City, CA, USA

14. Combat and Latency (1) NetGames'03, Redwood City, CA, USA

15. Combat and Latency (2) NetGames'03, Redwood City, CA, USA

16. Outline • Introduction  • Experiments  • Analysis • Application Level  • Network Level  • User Level • Conclusions NetGames'03, Redwood City, CA, USA

17. Bandwidth 3.8 Kbps 4.0 Kbps 6.8 Kbps NetGames'03, Redwood City, CA, USA

18. Inter-Packet Times NetGames'03, Redwood City, CA, USA

19. Payload Distributions NetGames'03, Redwood City, CA, USA

20. Bandwidth and Latency • Battle.net games had ~100 ms latency • Trace combat maps with induced latency NetGames'03, Redwood City, CA, USA

21. Payload Distributions and Latency NetGames'03, Redwood City, CA, USA

22. Commands and Latency • Pilot studies suggest 6 bytes of overhead per command • Remove 6 bytes from each packet payload • Add up remaining command payloads NetGames'03, Redwood City, CA, USA

23. Outline • Introduction  • Experiments  • Analysis • Application Level  • Network Level  • User Level  • Conclusions NetGames'03, Redwood City, CA, USA

24. User-Level Analysis • 0-500 ms latency, users could easily adjust • 800+ ms, game appeared erratic • Degradation in gaming experience • 500-800 ms degradation depended upon • User • More skilled were more sensitive • Strategy • Micro managers were more sensitive • Combat managers were more sensitive NetGames'03, Redwood City, CA, USA

25. Conclusions • Typical Internet latencies do not significantly affect user performance in Warcraft III • Some effect on exploration • No statistical effect on building or combat • RTS game play emphasizes “strategy” (which takes 10s of seconds or minutes), not “real-time” • RTS games less sensitive to latency than are FPS • RTS in QoS class similar to that of Web browsing • At the network level: • Small packets with low bandwidth • Command aggregation at higher latencies NetGames'03, Redwood City, CA, USA

26. Future Work • Effects of latency on user strategies • Other RTS games • Age of Empires • Command and Conquer • Effects of latency on other genres • First Person Shooter • Role Playing Game • Effects of loss NetGames'03, Redwood City, CA, USA

27. The Effects of Latencyon User Performance in Warcraft III Nathan Sheldon, Eric Gerard, Seth Borg, Mark Claypool, Emmanuel Agu Computer Science Department Worcester Polytechnic Institute Worcester, MA, USA http://www.cs.wpi.edu/~claypool/papers/war3/