Surely, 1993’s Myst is the oddest mega-smash in modern entertainment history. With 3.5 million copies sold (it still regularly tops the sales charts), the CD-ROM adventure heralded the arrival of multimedia as a mainstream commercial force. Yet playing the game underscored how new and problematic this medium is. Here was a fantasy world in which most of the story had already occurred, in which the characters had left the stage — and in which your job was to expend hours clicking through breathtaking vistas and knotty logic puzzles simply to recover the narrative. It was as if George Lucas had filmed empty Star Wars sets after the actors had gone home and left it up to you to figure out what had happened.

That hardly sounds interesting, yet anyone who has played Myst knows its hypnotic pull. And with the Oct. 31 release of Riven (Broderbund, for PC and Mac, $50), the long-awaited sequel to Myst, creators/brothers Rand and Robyn Miller have improved on the basic concept in all the best ways. You’re still navigating through a largely unpeopled land; you still gather fragments of story line slowly, through what you stumble over and play with and learn. But this time the Millers’ world breathes.

The water on the ruined archipelago of Riven glimmers with sunlight. Flies buzz; hawks soar; sea beasts dive off rocks with a resonant growf. You swoop between islands on a cable car out of Blade Runner by way of Jules Verne. When you near a group of huts, villagers scamper away in the distance, and the effect induces goose bumps; it’s as if a picture in a book has suddenly moved. And as you near Riven’s endgame, full-motion video scenes kick in — featuring strong acting and, necessarily, a ton of exposition.

On one level, this growth is due to the money and space that success brings: Where the single-disc Myst was cooked up on two Macs in a garage, Riven‘s unbelievably rich visuals (detailed enough to require five discs this time) were created on 13 Silicon Graphics workstations, just like the ones the Lost World boys use.

But there are signs of greater artistic assurance, too. While Myst‘s puzzles stuck out like a Parcheesi board in The Hobbit, here they tuck nicely into the story line. Riven picks up where the earlier game left off: Atrus, a builder of worlds in the form of books, has imprisoned his fascistic father, Gehn, on one of the latter’s creations, Riven. Atrus’ wife, Catharine, has been imprisoned by unknown forces on Riven. Meanwhile, Gehn is threatening to escape and cause havoc in the known universe. The official goal of the game is to rescue Catharine and trick Gehn into a new prison; I say ”official” because the real pleasure lies in the process, in the way that, say, learning about the Rivenese language system helps you ultimately contact a native rebel group fighting Gehn.

Hardcore gamers will want to crack Riven unassisted, but for players like myself, bred on fusty noninteractive media like movies and novels, I say there’s no shame in a judicious use of the book Riven: Official Hints and Solutions (Brady Games, $19.99). The point here is not frustration because you can’t solve the Fire Marble Puzzle. The point is the very human sorrow revealed in Catharine’s diary, the awe invoked when a primeval Wahrk swims up to a viewing window, the delight when a door opens to reveal a landscape you couldn’t have imagined before. Riven would make a terrible movie — and I mean that as the highest praise. A