With a gentle nudge, Ryan Griffiths tossed a small sphere onto a table and watched it stop on a magnetic trading card and pop into an action figure called a dragonoid, one of the Bakugan Battle Brawlers.

"It's the hottest toy right now," said Ryan, 14, of Wilmington, Mass., who attended a recent Bakugan training demonstration at Wal-Mart in Walpole. "It's a toy and card game at once."

Bakugan (pronounced BACK-oo-gon), which means "exploding sphere" in Japanese, has indeed exploded onto the toy scene in the United States since it was introduced in January. Its Toronto-based manufacturer, Spin Master, expects to sell $100 million worth of the games, cards and characters in the United States this year. The company estimates it will produce 40 million Bakugan spheres in 2008. Last year, it was one of the bestselling toys in Canada, where it was introduced in the summer.

The game combines the shooting strategy of marbles with the spirit and looks of Pokémon and the shape-shifting ability of Transformers robots. Bakugans are invading homes, backpacks, day-care centers and desktops nationwide. A cartoon series of the same name premiered on the Cartoon Network in February, fueling the Bakugan buzz among children, especially boys 6 to 11, who are dipping into their allowances to buy the characters and cards required to play the game.

It has all the elements

Toy industry specialists believe Bakugan has the potential to be another Pokémon.

"It's a combination of things," said Jim Silver, editor in chief of Toy Wishes magazine and Toy and Family Entertainment magazine. "It has the great elements of past successes. With the battling and the cards, it reminds me of the Pokémon. The other part is the collectibility to it. You want to collect different ones that have different powers. The key to a great game is that they are very simple to play but [with] a lot of strategy, and Bakugan has those elements."

Although they're small enough to pack in a pocket, the little creatures are making a big impact at toy stores, which have been selling out as soon as they hit the shelves.

"It's a top boys' property, and it's selling very well in our stores," said Toys 'R' Us spokesman Bob Friedland, who would not disclose sales figures.

Online sales filling in the gap

With the toys hard to find in stores, Bakugan is becoming a hot commodity online. The characters are popping up on Craigslist, eBay and toywiz.com, where parents and children plead for leads on where to snag the newest characters. A starter pack costs about $13, but people have been willing to pay much more online.

"One was selling for $150," Doreen Griffiths, Ryan's mom, said of her online searches. "They are in demand. We never find them at Target or Wal-Mart."

Once parents and children finally find the game, they discover that it's easy to play. Children throw magnetized plastic marbles onto a game board. Tucked inside the spheres are monsters modeled after dragons, tigers, snakes, centipedes and other critters. When the sphere lands on a magnetic card, it stops and unfolds into one of the creatures.

If two brawlers land on the same card, they do battle. The players flip over that card to discover the number of points that correlates to their characters. Each player adds or subtracts that value from his character's value, and the one with the most points wins and takes the other player's Bakugan.

"It taps into what boys want: battling, collecting and winning," said Dale Gago, a publicist for Spin Master. "It's not a technology toy that you sit in front of the computer and play. It's one of those timeless games. People have called it the marbles of the 21st century."

The monsters are on tour right now. Professional brawlers called Battle Masters are giving demonstrations at toy stores for children interested in learning how to play or looking to play with others.

Ryan's mother said the game has opened up his world. Ryan, who is autistic, owns 22 Bakugan characters, and plays at home with his mother or father.

"It's hard for me to get him to interact with other kids," Doreen Griffiths said as she watched him teach other children how to play. "It's great to see him want to do something other than be at home. He knows everything about the game."