His new project, "Uru: Ages Beyond Myst," is an immense challenge, but it has stunning potential to dynamically evolve as its developers enrich the game with updates over the Internet.

A few sequels after 1993's "Myst," Miller thinks he's found the secret to luring gamers back to the intricate, photorealistic worlds fans have come to expect: give players the freedom to roam three dimensions, let them play in groups over the Internet and provide lots of new content.

"In some ways the title itself — 'u' 'r' 'u' — we're trying to let you be yourself or anyone. You act as if what you would do if you were there," he said. "What would you be interested in exploring, what role, would kind of be the essence of things."

"Uru" is more akin to the casual online social experimentation offered by games like "The Sims Online" or "There" than the frenzied dragon-slaying addiction that fuels fans of "EverQuest" and its kin.

"Uru" has no economy, no swords or laser blasters, no knights in shining armor and absolutely no killing. There's no game-over screen. Rather, the player's goal is to explore the vast worlds left behind by the now-extinct D'ni civilization and share what they've uncovered with others.

As the Myst story goes, the D'ni wrote so-called linking books, which act as portals to different worlds, called ages. In the game, readers travel to the worlds by pressing their hands on the inside cover of the linking books.

The longer you play, the more linking books you'll acquire, and the more you'll be called on from others for help and hints.

Gamers can enter the world alone or in groups, spending hours exploring the remains of the D'ni and solving intricate puzzles to unlock doors or secret passages.

One puzzle involves setting a telescope so it follows the path of the sun. Once properly aligned, the incoming solar energy powers a nearby machine that gives the gamer the chance to delve farther into the world.

Teamwork will be essential, with many of "Uru's" puzzles requiring two or more people to solve. Players will be able to talk to each other in real time over their Internet connections.

Analysts say "persistent worlds" like Uru represent a tiny fraction of the $10 billion video game industry. Few games besides "EverQuest," which has a half-million players, have garnered a large following in the United States.

"These are big gambles," said Jay Horwitz of Jupiter Research.

The reason: Getting casual gamers to flock to such worlds could be tough. Miller envisions gamers spending about half an hour a night playing "Uru," with perhaps longer stints on the weekend.

Five years in the making, "Uru" is the only game in the pipeline for Miller's Cyan Worlds Inc., tucked away on the outskirts of Spokane.

The company has devoted 10 years to all things Myst, from the games to soundtracks and T-shirts — even a series of novels.

When it hits stores this fall, "Uru" will include a single-player mode that won't require an Internet connection. For a yet-to-be-determined monthly fee, players will be able to join others in the online version.