HOW TO SATISFY HIS JIGSAW JUNKIES IS NO PUZZLE TO STEVE RICHARDSON

Year after year in an immense, empty gallery of his pleasure dome, Xanadu, the aging megalomaniac Charles Foster Kane watches his lonely wife, Susan, piece together enormous jigsaw puzzles. "One thing I've never been able to understand, Susan," says Citizen Kane. "How do you know that you haven't done them before?"

She would know if she had done one of Steve Richardson's handmade, custom-designed tours de force of the jigsaw art. Richardson is the visionary behind Stave Puzzles, which he runs out of a two-story addition to his house in Norwich, Vt. He's a slightly dotty, fiendishly clever former math and computer-science whiz, whose outfit makes the most insidious jigsaw puzzles in existence.

Richardson, 44, recites a thesaurus of chicanery when discussing how he treats his loyal clientele. "We want to trick, fool, bamboozle and throw them off course," he says. "The thing that keeps us going is the desire to drive people crazy."

Stave puzzles seem to be for people with a lot of money and time on their hands. They start at $185 for a 135-piece puzzle. He has 300 people on his mailing list, and his regular customers, some of whom buy one a week, include Du Ponts and Mellons. Each puzzle is cut, painted, polished and counted by hand. Richardson uses five-ply wood with quarter-inch-thick mahogany backing. No two puzzles are cut the same way.

For an orienteer, he made a $1,200, eight-layer, three-dimensional, 800-piece puzzle based on a topographical map of the Quabbin Reservoir area in central Massachusetts. For a San Antonio divorcée awash in oil money, he's cooking up a 50-section, $70,000 extravaganza that, when she finishes it, will be a 120-square-foot rectangle depicting a photographic collage of Cooper Edens' paintings. Its 52,000 pieces will be the most ever in a jigsaw puzzle.

If Richardson makes a puzzle too easy, he gets mock-angry phone calls and telegrams. So he uses 25 different tricks, many of his own invention, to confound his jigsaw junkies. If this were football, Richardson would be called for unsportsmanlike conduct. The cardboard jigsaw puzzles you used to put together in summer camp had straight edges and corners, and you could work from the outside in. Richardson often takes away the outside and makes irregular edges, leaving the poor puzzler no clues.

Like a modern novel, many of his puzzles have no beginning or end. He leaves holes in the middle and carves straight-edged pieces in the center of the puzzle. Concealed in Stave puzzles are hidden messages, rebuses, secret logogriphs and puzzles within puzzles. Perhaps Richardson's dirtiest trick of all is to throw in extra pieces that don't fit anywhere. And never does he include a picture of the puzzle with the box.

"Richardson has changed all the ground rules," says Richardson, cackling. "There's a certain perverse pleasure my customers get out of the pain of putting the puzzles together. If we can really toy with a customer that way, we love it."

This summer Richardson came out with what he calls his greatest conceptual breakthrough. "I wanted to come up with a real killer, because some of these people were humiliating me," he says. "They know how to goad me on. If they finish a puzzle too fast, it drives me crazy."

So he designed a puzzle in which one piece will interlock perfectly with two other ones. "It used to be that the challenge was to fit the pieces together," he says. "Now the question is, is it the right fit? Richardson has pulled the rug out."

He punched some numbers into his desk calculator. "Let's see now," he says with devilish delight. "Two times two times two.... Hmmm. There are 1,048,576 different roads you can go down, but only one is the correct one. Aha.... Aha.... Ahahaha!"

Richardson's pi√®ce de résistance comes in the shape of a tropical fish of 150 pieces that he calls a piranha. If a customer completes the piranha within 24 hours on the honor system and solves its hidden riddle (Hint: It's written in braille), the successful assembler gets a $50 silver necklace bearing the company logo, a clown.

Out of the first 25 buyers, at $295 per puzzle, only five virtuosos have won the prize. The rest were outpuzzled. "Talk about panic building for them!" Richardson exults. "One of my customers told me that when his dog gets rabies, I'm going to be the first one it bites."