Released this week in PlayStation format, Riven is a sequel to Myst, the remarkably successful game which has topped the US charts since its release in 1993 and rivals even Windows NT in sales figures - several million at the last count. Rand Miller, who created Riven and Myst with his younger brother, Robyn, doesn't see Riven as a sequel. It's more of an evolution.
"I can picture exactly what went through Tolkien's mind right after he finished The Hobbit," Rand says. "It was somewhat whimsical and simplistic, but he could see the potential. `I am going to take this to a whole new level - I'm going to really fill it in'. The story is a small window into this world. Even Star Wars seems like only a window into a much bigger world somewhere out there."
The desire to create worlds was inculcated, or evolved, early on in the Miller boys as they grew up with two other brothers in Albuquerque, New Mexico, where their father was a Christian pastor. There was a freedom to explore creatively, as Rand, now 39 and with three young daughters of his own, remembers. Books, films, pictures - everything was drip-fed into an imaginative forum. "My mother was incredibly, almost overly encouraging. She would come up with the least little picture we had drawn and it was the most wonderful thing ever. Looking back, it's ridiculous, but it must have had an effect.
"After Myst's success, Robyn was saying we ought to make a movie, and Mum would say: `Where did you get that self-confidence? This is dangerous'. She was serious, and we said, `Are you for real? It came from you - we think we can do anything'."
Rand was heavily into computers by his teens: he would root out passwords from rubbish bins outside the University of New Mexico, and, a true child of his generation, built his first computer from scratch.
"It didn't even have a floppy disk, but you could play games on it," he recalls. "The first was Lunar Lander: it had no graphics, only text. I wanted to write a game, but I had no idea how to program. So I asked a computer student, and said, `I know how to print things out, but what's the command to make the computer think?' I didn't understand that you had to actually spell it out. It was a rude awakening; a lot more work than I had anticipated. My first game was called Swarms."
Nevertheless, after dropping out of college and becoming a programmer in a bank, he caught on fast. Meanwhile, Robyn, five years younger, was frustrated by computers but immersed in art and music. "You had to do things at too low a level for what he was interested in. It wasn't until the Mac came along that he saw the potential, where the computer got out of the way," says Rand.
It was in 1987 that Rand and Robyn began to work together part-time, at first on children's software. "There wasn't a lot of good quality stuff," says Rand. "Most people looked at it as an easy way to get in, so it was pretty trashy stuff. We discussed the fact that software should be like a good children's book, which even adults should enjoy.
"The Manhole [their first game] was basically a world which children would explore, with odd creatures and whimsical sounds. Robyn wanted to know what was down the manhole. He drew it, but he never got off the first page. It was probably more revolutionary than Myst or Riven, because the new idea was to build this world that was tantalising to a broad sweep of people."
When the brothers decided to turn to the adult market - which at the time was swamped by the Mario Brothers craze - they worked along the same lines. Like CS Lewis before them, they decided that in what was to become Myst, death would lose its sting; no more "Game Over", only infinite life. "We didn't want to keep starting again," Rand explains. "We thought, `Let's make the world big enough so you can keep going.' It seems so obvious to us now, but we had no idea it would be so successful. We said, `Wouldn't it be good if we sold 50,000?'"
Adults, naturally, would demand a greater degree of sophistication in their games. "We were doing this for guys in their twenties and thirties; doing it because this was the kind of thing we wanted to play," Rand says.
It would be harder to keep grown-ups enchanted; the challenge was to weave an utterly believable spell. "We asked, `What things break the spell and take you out?' It was common sense things. You didn't need a lot of bells and whistles and extra things; you didn't need dialogue boxes. You need to integrate things well. We're used to having sounds that fill every space, even quiet ones. We're used to seeing images very detailed, with a tremendous amount of texture."
Myst draws the player into the world of Atrus and Catherine, who live on Myst Island (taken from Jules Verne's novel The Mysterious Island). By solving a series of logical puzzles, the player is transported into different ages, and the "myst"-ery begins to unfold - although nothing is ever as it seems. Rand and Robyn played the characters on video footage for Myst; for Riven, they employed actors.
The rich and deep seam of storyline is, possibly, what gives the edge to the brothers' creations. Everything is believable once you enter their parallel universe; there is history, language, tradition, culture and masses and masses of texture. Josh Staub, who was lured into the Millers' fantasy world after striking up a friendship with their younger brother, Ryan, is now art director for the Millers' company, Cyan, based in Spokane, Washington.
Steven Spielberg's Jurassic Park and Terry Gilliam's Brazil were influences for the computer-generated imagery Staub produced for Riven, using more than 60 Silicon Graphics workstations to smooth out the movements of characters on screen. He says of Softimage, the company with whom Cyan worked to manufacture and tweak the necessary technology: "They weren't super-responsive in the beginning because we were making a game, but the scenes we were creating were so complex and so huge that it wasn't long before we were rivalling the kinds of scenes in major motion pictures.
"We had scenes that had over 17,000 textures; a table might have 10 or 15 textures. Softimage couldn't believe it: we were definitely pushing the envelope." One American critic, on seeing Riven, called the effects "profligate, brazen, unnecessary". "It's a gift that borders on obsession; it makes you grateful and nervous at the same time."
Under the guidance of Richard Vander Wende, the art supremo behind Disney's Aladdin - who became part of Cyan's triumvirate of power after the success of Myst - the Miller brothers and Josh Staub used rock surfaces, adobe walls - even the surface of a human palm - to form the minute details of texture in Riven. Some of the artists got so engrossed that tiny objects became full of unnecessary detail, according to Staub.
"Whenever possible, I was trying to think of things to interact with the environment," he says. "Most companies have real sets and are putting fake creatures into them. We did the opposite. For instance, you see a guy reaching through the bars to take a book from you, so we needed shadows on the bars. We even had him shaking the bars a little, which made him look like he was real."
There were plenty of frustrations. For a start, Riven was no longer a "garage project", as Myst had been. Now, the brothers had an office, a budget - and staff. Their relationship had also necessarily been forged anew. Rand describes himself as the self-motivated one, with the knowledge to put a game together, while Robyn is creative. But it's not quite that simple, Rand says: "We both come up with ideas, and he knows enough about programming to challenge me. Working with partners is dangerous, and somewhat of a marriage. It's a lot of hard work, but with brothers particularly, you grow up arguing, although it's not like you're going to leave each other. You learn to solve your arguments early on."
Another frustration for the brothers was the inability of the game-form to evoke emotion in the same way as, say, a film or a book. Rand Miller says: "It's very easy in a linear story, because you have such control. Every minute, every second, is manipulated. Sometimes it's done cheaply and not responsibly, but when it's used properly you can teach valuable lessons. Emotion is something which imparts lessons when you're feeling involved with the story."
One senses that this is his goal - not to be didactic, but to open players' eyes. In fact, the games are tested in a room where the designers can watch players' reactions. Rand concurs: "You look at someone like CS Lewis, where there's a good story but another level underlying it. It's not beating in your head with some kind of lesson, but it's there for those who have eyes to see it. There was a level of frustration, even with Myst and Riven, that there wasn't a lot of meaning. There was an intent to put some in, but we struggled with learning the tools and just getting it done."
It was a relief, he says, when Riven was finally finished last autumn, to be able to say to Cyan staff, some of whom had worked 18-hour days for a year: "Go home and enjoy life."
Rand himself still lives in a trailer with his family in the woods near Spokane; he took a month off after Riven and went to Hawaii for a break. Even now, he is recovering from the strain of getting the product on to the market, where it has been received with rapture. He indicates, albeit obliquely, that he and Robyn have come to some kind of impasse, or divergence of ways. Riven was the fulfilment of a goal; what next? A book? (Myst- related novels have already appeared.) A film? Robyn, apparently, is intrigued by the idea. Otherwise, they have been working on small projects.
"Computer games is a diverging, rather than a converging market. There are so many shoot-'em-ups," says Rand. He advises would-be designers to concentrate on innovation rather than cave in to popular demand. "I don't see barriers but opportunities; we look at where technology is going and see new areas. One is obviously the Internet, where things are not static, not stamped on to a CD-Rom. But it's all early days because there's not enough bandwidth, It's hard to predict, but just seeing the potential is amazing."
However long it takes, the Miller brothers' audience will hold their breath. With so many potential worlds out there, it's only a matter of time before they open another window.