Jack Lyons of Wilmington hands out triangle-shaped business cards. Last Christmas, he baked triangular cookies for the rest of his family. He wore a triangle-shaped hat to the 2009 Sudoku National Championship in Philadelphia.

"I think he thinks in triangles," said his mom, Louise Lyons.

Apparently, it paid off. Seven Footer Press of New York just released Lyons< book "PyRuKo: The New Logic Puzzle That<s Not for Squares" (\$7.95 paperback), a collection of 120 brain-teasers. On April 29, he<ll be host for the first PyRuKo contest at the Sudoku Internationals, also planned for Philadelphia. If Lyons has his way, thousands, perhaps millions of Americans will be starting their mornings with PyRuKo puzzles, just the way they warm up with Sudoku. The new Sudoku, if you will.

So what<s PyRuKo?

Well, like Sudoku it<s a logic puzzle. It uses the numerals 1 through 9, although, like Sudoku, it<s not a mathematical problem.

Unlike the rectangular Sudoku, however, PyRuKo is based on triangles.

A typical PyRuLKo puzzle — Lyons rates them from "Easy" to "Moderate" to "Challenging" — takes the form of an upside-down triangle. This big triangle is divided into four smaller triangles, each further subdivided into nine three-sided spaces.

Each of the spaces in those four small triangles will contain the numerals 1 through 9, with no repeats. Also, the three axes of the triangle will contain the numerals 1 through 9 with no repeats.

Some of the blanks on each puzzle are helpfully filled in. All you have to do is figure out what goes in the remaining blanks.

"You just go through and eliminate," Lyons said. If a 4 is here, for instance, it can<t also be over there.

Easy, right?

"If Mom can do it," Lyons said, grinning, "anyone can."

"It<s not like anything else we<ve seen," said Robert Kempe, marketing director for Seven Footer Press. "We think Jack has captured something clearly unique and captivating." A native of the Philadelphia area, the 43-year-old Lyons said he caught the puzzle bug early. "As a kid," he said, "I remember playing chess on a three-level board" — the "3-D chess" popularized by the original "Star Trek" series. After graduating from Ursinus College, he spent decades working in the information technology field for such companies as IBM, Hewlett Packard and Kaiser Permanente.

After visiting Wilmington for years — his mother moved here in 1993 and three of his four siblings attended the University of North Carolina Wilmington — Lyons moved here full-time in 2007, launching a small business in computer consulting and Web design. He also offers math tutoring on the side.

"I worked a lot of Sudoku, but after a while, it got boring," he said. "I thought, OK, there<s got to be a different way to do them. How about 3-D?<?"

PyRuKo evolved as a triangular puzzle although, the publisher points out, the puzzle triangles can be folded into tetrahedrons, or four-sided pyramids — with 1-through-9 numerals on each face.

The game had a positive response last year at the Sudoku nationals, where Lyons passed out hundreds of tear-off PyRuKo puzzles with the answers on the back. Since the event was in Philadelphia, the inventor had a chance to meet up with some boyhood chums and get in some hijinks.

"We<d sit in the audience in a triangular formation," Lyons said. What<s next? Louise Lyons says her son has a mockup for a three-diemnsional PyRuKo puzzle at hom — a sort of pyramid version of Rubik<s Cube. Jack Yons says it<s a work in progress.

He< also designed variations called Mega-PyRuKo, PyRuKo-X and Master PyRuKo, in which the triangles overlap, and each shares 1 through 9 blanks. "They<re even harder," he said, grinning fiendishly.