The Goal Of Everquest is to build the wealth and power of a mythological alter ego. You use keyboard commands to roam around vibrant virtual worlds that have a medieval look [see screen shots, "Like Magic"]. You see the world unfold in front of you: if you're climbing lush green hills, you see turf, trees, and rugged mountain ranges in the distance. If you're swilling mead in a musty tavern, you see something like the Cantina scene from Star Wars. If you're burying an axe in an ogre's back—well, you get the idea

You start the game by creating your alter ego. You might be a stout, bearded dwarf or a towering, bad-tempered troll. You might be a zombie-banishing priest or an axe-wielding warrior. You can choose everything from the hue of your character's skin to the hairstyle.

Once your character is complete, it's time to venture off into one of EverQuest's dozens of elaborately detailed virtual worlds, which contain whole continents to explore. Within the worlds, there are "burgs" to suit every kind of player—from hack-and-slash arenas where players take on other players to communal hubs for swashbuckling guilds. Some worlds have slightly different rules of play, but the main reason there are so many is simply to avoid overcrowding. At any moment, there are thousands of players online, so some locales in the game would become too crowded with creatures if not for the division into separate worlds

The game is played around the clock, so there are always creatures inhabiting the worlds. That feature is critical to the game's appeal—because the action continues even when you are not playing. The next time you sign on, you may find your world is different from when you played before. While you are logged off, your character is safe from harm. But a bathroom break can lead to an untimely death if the player doesn't log off before stepping away from the computer.

The basic idea is to develop your character by maneuvering it so that it accumulates experience and gets rich. Slaying a dragon, for example, is one way to riches. But that can be a complex affair. To do so, you probably would need to get together with some other players, because such a task usually demands the skills and brawn of more than one character. To collaborate, players use the game's messaging features. Convening in a virtual town, the characters head off together to find the monster in whatever dungeon it may be lurking, their corresponding players chatting about strategies along the way. Once they confront the creature, they combine their skills—swordplay, magic spells, and brute strength, say—to slay the beast and steal its loot.

The most devoted fans call the game "EverCrack" and might play eight hours a day. Singles even meet inside and get married, not only in the game but sometimes in real life as well. The obsession with EverQuest is so strong that an underground economy Sony unofficially estimates to be worth as much as $150 million annually has sprung up to support it. Players barter virtual items collected in the game on eBay. Once a coveted sword went for $1500. Really. Someone paid $1500 in real money so that his or her EverQuest character would be able to wield a desirable weapon.

EverQuest is not just a social phenomenon or a source of cash for Sony; it's also a phenomenal example of how a company manages rapid growth and the art—and science—of scaling up computing technology. More than 1500 servers around the world run EverQuest; collectively the machines have the bit-crunching capabilities of one of the world's top 100 supercomputers. In just one of the data centers, more than 30 kilometers of wire and cable connect all the boxes. More than 9 million gigabytes of EverQuest data have been downloaded from Sony's servers in the past six years.

It all adds up to a monster IT challenge. Although there are 13 data centers in Japan, South Korea, the Netherlands, and on both coasts of the United States, the heart of the monster resides in San Diego, at Sony's mission control. Its 45 occupants, the real-life heroes behind EverQuest, aren't wizards. They're engineers.