It's no longer enough for action movies to be amusement. Now they have to be amusement parks as well. They're blurbed as "thrill rides" and "roller coasters," and the more they follow the basic pattern of your average Nintendo game, the more highly they're touted. It was considered a breakthrough a few years back when a studio tested "interactive" movies, which gave the illusion of choice by letting audiences pick from different (fixed) outcomes.

Now, what would really be interactive would be for someone to say screw the movie and take a pickax to the screen--if not to the moviemakers themselves. And if you push audiences far enough, removing just enough of their sense of the familiar, they just might do it: All it takes is crossing the line from safe entertainment into uncontrollable chaos.

This distinction has haunted the work of director David Cronenberg for the last 20 years. In his latest film, the sense-deranging thriller eXistenZ, the potential for chaos exists at every turn--as befits a vision in which reality is manufactured, flesh fuses with metal, and organic guns shoot human teeth. Jennifer Jason Leigh plays Allegra Geller, the world's hottest game designer, who assembles an audience to preview her mind-blowing new VR creation "eXistenZ." At the test run, however, she learns all too vividly that she's under a death sentence from "realists," terrorists who see virtual reality as life-threatening--and will therefore kill to stop it. Soon Allegra is on the run through a surreal underworld, followed by a wide-eyed PR flack (Jude Law) who has never played a video game but will have to play hers. Naturally, there's a catch. Playing eXistenZ requires humans to plug the game directly into their spines, through an "UmbyCord" into an anus-like "bioport."

That's a lot to go through for cheap thrills, and lots of folks likely feel the same way about Cronenberg's gooey, horrific oeuvre. With its spurting goo, transgressive sex, futuristic paradoxes, and death matches of mind and flesh, eXistenZ is a Cronenberg career summation organized along the theme of interaction--not just between player and game, but between viewer and art. Once inside eXistenZ, Allegra and company pause to note the triteness of their dialogue, the inadequacy of their characters. You get the feeling the movie's eyeing you for a reaction.

Consequently, the movie plays tricks on what audiences want and expect from pop entertainment, be it a video game or a sci-fi thriller. Want blood? Cronenberg provides the requisite gory violence, only in such an arbitrary way it's exposed as shameless yahoo-pandering. Want a rational narrative? Cronenberg makes leaps of logic, character, and setting so baffling that they don't become clear until the end. Even then, the final outcome is so devious you'll sit poking yourself to make sure you won't disappear with the click of the projector. Only the dullest of brains could fail to interact with this gale-force mindfuck.

Still, Cronenberg has frequently contended with the dullest of brains--most recently, the reviewers who took the sex-as-collision simile of Crash as literal pornography. The writer-director has said the idea for eXistenZ came from the fatwa against Salman Rushdie, whose fiction provoked a potentially lethal real-world backlash. But the movie's "realists" could stand for all the pundits who point to scary movies and Sega whenever inexplicable real-life violence erupts. Even our president apparently sees no contradiction in chastising Hollywood mayhem, even as he OKs bombing the hell out of the Balkans. Subversive and sneakily funny, eXistenZ operates on just such levels of irony.