eXistenZ is a return to David Cronenberg’s early ‘body horror’ days, and a surprisingly successful one. If you’re one of the fans who felt short-changed by The Naked Lunch, and disappointed by Crash, this could lure you back. His best film since The Fly, eXistenZ takes the well-worn theme of virtual reality, usually a cue for much running about in steel corridors firing lasers, and gives it a makeover that grunges down the scenario and switches to a more cerebral state of play. Jude Law and Jennifer Jason-Leigh are on the run from realists who wish to destroy game-makers, ‘the enemies of reality’. Leigh is the designer of a new game, eXistenZ, and Law is the neophyte player, but the old chestnut - what is real and what is fantasy? takes on an entirely new twist precisely because the game they play is so much like real life.

Which means that instead of computer graphics and light-pulsing gadgetry we have the sights, sounds and textures of everyday existence. The eXistenZ machine is no gleaming plastic gizmo but a foetal organism (grown from mutant DNA in specially-bred organs) that jacks directly into the lower spine. Cronenberg has fun playing on some of our most personal fears, including loss of control and male penetration, then craftily ups the ante, hoodwinking the audience by overturning the scenario - but it’s best not to give too much away.

eXistenZ is prepared to divide its audience; it’s bleak and gory, but this time there’s a wickedly ironic sense of humour at work, while gameplayers and SF fans will start spotting clues to the puzzle early on. Everyone is playing to their strengths, Law is flawless, wide-eyed and virginal, Leigh at her strangest and most aloof. Ian Holm and Willem Dafoe deliver quirky turns as players who may - or may not - be trusted. Everyone speaks as if their dialogue is in quotes, and at first this disconcerting sidestep from normal film technique is extremely bothersome, but once you get the joke and settle in, the film becomes a hoot. Instead of extreme weapon-power, vast city vistas and epic quests, eXistenZ is a game that plays in a series of ordinary confrontations in small mundane rooms. It¹s rather like peering down into the gameplay from the wrong end of a telescope, and that’s what makes it so disconcerting. No giant serpent rears up in a welter of on-screen graphics to let you know you’ve lost the game, so how do you really know if it’s over?

All this cleverness will tax the patience of anyone who has never been near a Playstation, but it allows the director to explore some of the ideas first raised in Videodrome. Cronenberg uses deliberate pacing and intimate, low-key scenes to return to the kind of low-tech visceral shocks that work best with his anti-style. Our audience squirmed and wailed in discomfort whenever Law jacked into eXistenZ, and the Chinese restaurant scene will linger in the memory of anyone who has ever felt unsure of what they might be eating. Play the game and your patience will be rewarded.