Rated 4.0 Jennifer Jason Leigh plays the designer of “eXistenZ,” an ultra-realistic video game, who goes on the run with her bodyguard (Jude Law), pursued by assassins out to destroy her and her works. Writer/director David Cronenberg creates a shifting, ambiguous universe in which we, like the characters in the film, are never sure where reality ends and the game begins, or vice versa. It’s a disturbing, disorienting sensation—puzzles within puzzles, games within games—that continues right up to the last shot. The game’s modules are semi-organic creatures, indulging Cronenberg’s penchant for subliminal sexuality and squishy bodily fluids, that seem, like the game itself, to take on a life of their own.