While some victims have been white, and some suspected attackers black, experts said the incidents are more about preying on the seemingly helpless than race or religion.
"It's about someone who is seemingly helpless, and choosing that person to target," Butts said.
One victim in Washington, Phoebe Connolly, said she was randomly punched in the face by a teenager while riding her bike last Friday.
"I don't know what the goal was," she said. "There wasn't any attempt to take anything from me."
A recent media blitz about the game isn't helping, Connolly and experts said.
"The behavior of the sudden assault of someone who seems helpless has appealed to the idiotic impulsive quality of adolescence forever," said Butts. "But in the last 10 years, they've giving a name to this, and there are now bragging rights beyond your immediate circle, when this is on television and online."
In September in Jersey City, two 13-year-olds and a 14-year-old were charged as juveniles in the murder of 46-year-old Ralph Eric Santiago. He was found Sept. 10 with his neck broken and his head wedged between iron fence posts. Hudson County Prosecutor's Office spokesman Gene Rubino has said his office believes the teens were playing the game.
In May in Syracuse, a group of teenagers attempting to knock Michael Daniels out with a single punch wound up beating and stomping him to death, according to police. A 16-year-old was found guilty of manslaughter, and his 13-year-old co-defendant pleaded guilty to assault. Both were sentenced to 18 months behind bars.
And earlier in May, Elex Murphy, now 20, was sentenced to life in prison plus 25 years in St. Louis for killing a Vietnamese immigrant as part of the game in 2011.
Paul Boxer, a psychology professor at Rutgers University who studies aggressive behavior, said the media stories may perpetuate the assaults, but most teens clearly aren't unfeeling sociopaths.
"You've got some impressionable kids, already with a propensity for violence who could be affected by this," he said. "But not because they are hoping to hurt somebody, it's more about risk taking, and new, different and exciting ways of getting into trouble."
Juvenile delinquency experts say the best punishments for these teens would be empathy training, such as volunteering at a homeless shelter. But a New York lawmaker proposed a bill this week that would make stricter sentences not only for those who do the punching, but for those who publish images online and watch the attacks.
"These twisted and cowardly thugs are preying on innocent bystanders, and they don't care if the victims are young, old, a man or woman," state Assemblyman Jim Tedisco told The Associated Press in announcing what would be one of the first bills like it in the nation. "Life isn't a video game."
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Associated Press writers Mike Gormley in Albany, New York, Eric Tucker in Washington and Kevin Begos in Pittsburgh contributed to this report.