WESTBOROUGH - Sean Anderson ran around his house as fast as his 8-year-old legs would go while he and his dad fired at each other using tiny devices with blinking green and red lights.

Sounds like the typical pastime of a boy. The difference is, Sean was playing with his own invention.

Sean and his dad, Mark Anderson, were playing with prototype versions of a new trademarked and patented game they developed two years ago. By the holiday shopping season, roughly 25,000 units are expected to hit toy store shelves.

"One day my dad was watching TV and he would pretend to shoot the channel changer at me when I was running by. So I was like, 'Dad, wouldn't that be a cool game,' " said Sean, who was 6 when inspiration struck.

>From that, the simple idea of TinyTag was born.

The 2-inch-by-1.25-inch-wide units look like garage-door openers or key chains. Players use a single button to "fire" at each other. A player who's been hit six times looses, and the firing player wins.

"It is what it is, but everyone's telling us it's a good idea," said Mark.

Of course, Anderson likes to show off the trick shots by bouncing the TinyTag's beams off his hand or a wall to hit his target, or by hitting multiple targets with a single shot.

Producing the miniature game, though, is a family affair.

Anderson's "annoying" brother James, an 11-year old Mill Pond School student, leant his voice to the gridiron grunt noise, celebratory "winner" and smug "loser" sounds. He also heads up the Street Team, which promotes the product.

"I made the grunt sound after Sean punched me," admits James while tackling his brother football-style.

The boys and their father also make a point to note that mom Kathleen (Katie) Anderson works on sales of TinyTag.

"She was mad we didn't mention her on TV," explains Sean who often slides across the kitchen floor on his knees without warning.

Katie Anderson has every reason to be proud of her son. Not many second graders are paid a visit by the television cameras of New England Cable News, but then again, not many are listed as co-inventors for a product first modeled with Lego building blocks.

Anderson unveiled his invention to his teacher Kerry Ciccone and his classmates at the Fales Elementary School last week.

"My art teacher saw it and said it was cool," said James.

The device, which is available in black or a glow-in-the-dark green, works on the same technology as remote controls with infrared beams, and is meant for indoor or low-light use.

The Andersons' neighborhood friend Matthew Van Maszewski developed the software in TinyTag's three centimeter by three centimeter microprocesser, and Van Maszewski's uncle Bob who worked for NASA improved the device's firing range to 50 feet.

"Even up to last month we were asking, 'Is this possible?,' " said Mark, who developed the business plan for TinyTag, SeanO Toys and SeanO Corp., the organizations created to manufacture the game.

"We took apart everything in the house to figure out how to do it," said Sean, who lists Play Station 2 and Nintendo's Gameboy as his favorite toys.

Mark, a former vice president for an Internet company and now the president of SeanO Corp., said that trying to find financial backing and a manufacturer for the project was difficult last year in the wake of Sept. 11.

So the dedicated dad researched and obtained a small business loan from the federal government on his own and found a 150-person company on the Internet which agreed to manufacture the toys in China at a cost the Andersons could afford.

Once that hurdle was crossed the Andersons also had to deal with the recent California dock strikes.

"We're actually thinking of leasing a 747 to fly them here from China," said Mark. "And Lloyd's of London is insuring them when they get here."

TinyTag is expected to sell at a retail price of $14.99, which includes two game devices. More information is available at www.SeanO.com.