1. Small group multiplayer games

2. Introduction Modern games have: z3D graphics znice music and sound effects zinteresting story zmultiplayer mode

3. Definition “Small group” multiplayer games ztypically 16-32 players in one game zdirect interaction between all players zusually all players have to be present when the game starts

4. Communication Architectures How do networked computers exchange information with each other? zClient-Server zPeer-To-Peer

5. Client-Server zAll information is sent via a server, not directly between clients.

6. Client-Server Advantages: zonly one connection per client zminimal network traffic zgameplay management tasks zcheat / hack protection

7. Client-Server Disadvantages: zhigh network latency zlimited capacity

8. Peer-To-Peer zAll information is exchanged directly between players.

9. Peer-To-Peer zfast information delivery zno need for servers zvulnerable to hacking znetwork traffic can be high zhow do players find each other?

10. Matchmaking Services Meeting places for players zcreate and join games zchatrooms zplayer profiles zcompetition (ranking, tournaments...)

11. Matchmaking Services Examples: zBlizzard Entertainment’s battle.net™ (http://www.battle.net) zNet-Games’ FSGS™ network (http://www.net-games.com)

12. Dynamic Shared States = information shared by multiple machines zplayer positions and actions zstatus, health, weapons,... zworld properties (weather effects,...)

13. Dynamic Shared States zGoal: give the illusion that all players are seeing the same things at all times zProblem: network limitations  information may arrive too late  information may change too frequently

14. Dead Reckoning zaccept potential discrepancies and try to approximate shared states zsend extra information (e.g. player speed and direction) used by: simulations, 3D shooters,...

15. Delayed Reaction zdelay all local actions by a certain amount of time zresults in very consistent shared states znot suitable for all games used by: strategy games (e.g. Starcraft)

16. Summary Communication architectures: zClient-Server zPeer-To-Peer Network limitations: zlatency, bandwidth