FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
PROBLEMS WITH LOCAL PLAY
Local play as just described presents the game designer with serious difficulties. For one thing, because all the players share the same TV, any user interface elements displayed must be duplicated for each player, taking up valuable screen space. If the game maintains a separate point of view for each player, you must subdivide the screen into little windows. Each player will find it harder to see a small individual window than the full screen image, and activity in the other players' windows will distract him.
More important, however, because local play uses a single display device, you have no way to hide information. Each player can see everything the others do. This works well for fighting games, but not as well for any game in which players might want to keep their activities secret—war games, for instance.
Finally, local play necessarily imposes limits on the number of people who can participate at one time. Consoles seldom support more than four players; PCs support even fewer. Even if you could add players indefinitely, the screen would become crowded with characters and other data, and the machine itself would bog down as the computing tasks grew.
Online gaming solves all these problems. Each player uses her own screen, and the entire display supports only her gaming experience. The game can present her with her own unique perspective, including exactly as much information as the designer wants her to have and no more. And online games can support large numbers of people (although games requiring a central server may find the server capacity limiting); it's not uncommon for some games to support tens of thousands of players online at a time. With an online game, players can always find other people to play with at any hour of the day or night.