There are precedents for ''Artery,'' but I've never seen a show quite like it. There's just one performer, and one member of the audience, and both of them are you. An usher hangs a Sony Walkman tape player around your neck, plunks a set of earphones on your head, and points you to the beginning of a long, twisting maze. From there, you're on your own for 50 minutes - threading your way through the labyrinth with friendly instructions from a tape-recorded narrator.
Yes, there's a story, unfolded by the narrator-guide. It's about a man named Jay, played by you. He dreams of ritzy living on the Riviera, but his life is small-time all the way, complete with bad fortune and troubling memories. Other characters (you hear their voices on the tape) include girlfriend Louise and her brother, a policeman.
As the show proceeds, you walk through Jay's experiences. Following the narrator's directions, you open a door or stroll down a hallway - and find youself standing in a living room, sitting in a restaurant, plunging into a (make-believe) swimming pool, or lounging in a dream sequence on a European beach. At one point you even steal Louise's jewelry, slinking away like the proverbial thief in the night - but don't worry, it's all in fun, and you get your just deserts in the end.
''Artery'' was created by Chris Hardman, the founder and honcho of Antenna Theater, based in Sausalito, Calif. I caught it during its current run at the Performing Garage in lower Manhattan. It's a modestly budgeted show, creating its effects and environments with simple materials (thin wooden panels, flashlights, strips of plastic dangling from the ceiling) and generating its fun with ingenuity instead of razzle-dazzle.
The story is thin, sometimes vague, and occasionally confusing - it wouldn't interest me much in a conventional production. But the possibilities of ''Walkman theater'' are enormous, I think, and deserve to be fully explored by inventor Hardman and the others who will surely be inspired by his example.