If you want to understand the Matrix trilogy, think of it as a capsule history of baby-boom rock. The original Matrix is a three-chord riff of a movie: a simple, familiar idea—"What if reality is a great big fake?"—amplified and transformed into an irresistible hook. The Matrix Reloaded is a 1970s prog-rock concept album: sprawling, pretentious, and ultimately incoherent, but brimming with ideas and virtuoso displays. And The Matrix: Revolutions is an over-the-hill pop star recycling someone else's material—the sort of music you'd hear on a Michelob commercial, circa 1987.

Even if Revolutions weren't already slated to be the final installment, its chilly critical and commercial reception should guarantee we won't find ourselves awash in ads next year hyping The Matrix 4: This Time, It's Personal. Less obvious is the fact that this turgid tale marks the decadent stage not just of a Hollywood franchise, but of a briefly vibrant genre. In the late '90s and early '00s, a wave of films played with the notion that what we experience as "reality" is a false and perhaps malevolent illusion. The idea wasn't new—it was at least as old as Plato, and it had provided a backbone for many movies already—but suddenly it was everywhere: in The Truman Show (1998), Dark City (1998), The Matrix (1999), the Canadian eXistenZ (1999), The Thirteenth Floor (1999), the TV series Harsh Realm (1999-2000), Waking Life (2001), Vanilla Sky (2001), and others. The broader idea of prowling about in someone else's virtual world turned up in still more stories, from What Dreams May Come (1998) to Being John Malkovich (1999) to The Cell (2000)—even the occasional kids' cartoon. The quality of the films varied widely; the idea at their core did not.

Some of this was surely just imitation, but too many of the projects were created simultaneously and independently for that to explain everything. For whatever reasons, audiences at the turn of the century were receptive to paranoid thrillers about inauthentic realities. Call it the Demiurge cycle, after the Gnostic notion that our world is governed by a mad ersatz God.

With Revolutions, the cycle stops. Not because hardly anyone seems to like it, but because, unlike its two predecessors, it scarcely bothers to engage the idea that set the Matrix trilogy in motion. No longer trapped in a false world devised by an evil intelligence, our heroes are now trapped in an anthology of war-movie clichés; no longer skeptical and alienated, they repeatedly proclaim the tritest sort of faith. When critics comment on the Gnostic-conspiracy genre, they usually cite the novelist Philip K. Dick as its patron saint. Well, there are no traces of Dick in The Matrix: Revolutions, unless Dick secretly ghostwrote an episode of Battlestar Galactica.

Of course, Dick's work goes further than most of these films do. If the king of the world-builders was J.R.R. Tolkien—the man who devoted so much of his life to creating the Middle-Earth of The Lord of the Rings, complete with an elaborate philology for his imaginary languages—then Dick was the fellow who confessed, in an essay called "How to Build a Universe That Doesn't Fall Apart Two Days Later," that he likes "to build universes that do fall apart. I like to see them come unglued, and I like to see how the characters in the novels cope with this problem." In a Dick story, true as well as false realities threaten to crumble away, and false as well as true realities are waiting to be discovered.

Only a few of the recent films—notably eXistenZ and Being John Malkovich—are willing to take things that far. As a result, most of them never recognized a curious social fact that lurked in the background while they flickered on our cineplex screens. In these movies, either the protagonist or the whole world is trapped in an alternate universe of someone else's making. Yet the films emerged as more and more people were quite willingly immersing themselves in alternate universes, many of which they helped to build. The world of the Web, of multi-player video games, of fan communities, and so on is one in which people adopt or construct their own fake realities, which then bump up against one another in unpredictable ways.

Granted, that describes all social interaction. But there's something especially interesting about this latest variation. The paradox at the heart of The Matrix is that a story about people struggling to free themselves from an imaginary world should evolve into an imaginary world that millions of people are eager to enter. You can become a Matrix character by playing a bestselling video game; you can explore the Matrix universe by playing a collaborative online puzzle-game; you can build unauthorized add-ons to that universe by devising your own Matrix parody or fan fiction. People might not like to be forced or tricked into a false world. Evidently, though, they'll jump at the opportunity to enter and exit one at will.

After watching Revolutions, most may opt to exit. But there are many more consensual bubbles out there waiting to take its place.