How It Works: Online Gaming

Net gaming: playing competitive or cooperative computer games with multiple users on a local area network or the Internet.

Pong is so over. Why play games against a computer when you can match wits with a living being? Thanks to network gaming, you can vanquish an opponent that doesn't even live in this hemisphere. Net gaming connects you with players around the world and puts you in an environment where you can compete against each other in real time.

Here's what you need to know:

• Net games use servers to manage action between players, while your computer handles graphics and sound.
  
  
• You can choose from a wide variety of games, from poker to shoot-'em-ups.
  
  
• A fast Internet connection means you can play sophisticated games without too many lags.
  
  

As the name implies, a network lies at the heart of Net gaming. Generally, the network comprises one or more computers that act as servers, and computers on the players' desks known as clients. Clients connect to the server via the Internet (or to a server on a local area network). The server does the housekeeping for the game--choosing which game is being played, keeping track of who's playing, and sometimes even offering chat between players.

During game play, the server tracks the movements of all participants. When players move, fire a weapon, or play a card, their computers send "state of the world" messages to the server. The server then transmits these messages to the other client machines.

This lets movements you make during game play appear on other users' screens. The client computer then supplies the graphics and sounds, filling out the visual experience for each player.

Central and Distributed Servers

Net games can be divided into two classes: Those available from centralized servers and those that run on distributed servers. Centralized servers usually house games that allow thousands of users to participate at the same time, as is needed in massive role-playing games such as EverQuest.

For these games, much of the information about the environment is contained on the central server. The game world exists 24 hours a day, so the game continues whether you participate or not. In RPGs, the game never really ends; you can keep playing until your character dies. To play, users launch the client software, which then logs on to the game's master server.

In a distributed scheme, server software resides on several dedicated game servers or on individual players' PCs. Real-time strategy games such as Myth and 3D shooters such as Quake III Arena use this model. These games require more frequent "state of the world" updates. Distributed servers spread the load of messages out; a single server would have a difficult time keeping up with thousands of Quake players.

The game servers send messages every few minutes to another machine called a master server. The master server exists only to maintain the addresses of all active game servers. Anyone who wants to play must first get that list from the master server.

Players then query individual servers in the list for information about the type of game on that server; the number of players; and the "ping time," or time it takes for commands to reach the server and return to the player. Players usually pick a server with the shortest ping time and then connect directly to the game server.

Some Net gaming services, such as WON.net, use a combination of centralized and distributed servers. In these setups, distributed servers control game play, while centralized servers handle extras such as real-time chat between players and player ranking services.