Phillip Jasper saw his chance. His older brother, Michael, was on the other side of the tennis court. He grabbed a melon-sized rubber ball and flung it toward him.

What Phillip didn't see was another ball heading in his direction. Until it drilled him in the lower jaw.

He fell, writhing in pain, his hand massaging his face. Then he picked himself up and walked off the court. His 17-year-old brother was untouched.

"That hurt a lot," the 15-year-old said. In a few minutes, though, he was back on the court.

There's nothing genteel about summer dodgeball at Tilden Woods Park in Rockville. When the sun goes down and the lights go on, about 40 teenagers, male and female, line up on opposite ends of the court with a simple goal: hit one another with a rubber ball. Hard.

There are no referees, no time limits, no over-caffeinated parents trolling the sidelines. The rules are minimal. Each night, they play as many as 20 games, but no one really keeps count. They don't wear helmets or kneepads. Sometimes 40 show up; sometimes a dozen. Sometimes they play on weekends; sometimes they don't. People come and go as they please.

"This is the place to be at night," Phillip said.

In a county where many teenagers are fully booked with internships, camps or full-time jobs over the summer, these young men and women relish the moment each night when they can get together for some unstructured fun. At Tilden Woods, the evenings evoke an era when kids had to use their imaginations to fill the time when school was out.

"It's nice to play dodgeball after a stressful day of sick animals," said Phillip, a student at Walter Johnson High School in Bethesda who is a veterinary technician this summer at a Montgomery County animal hospital.

Most nights, they start about 8:30, taking breaks only when the lights go out for a few minutes each hour. They quit when the lights turn off for good at 11.

Dodgeball was once a playground favorite, but its popularity plummeted when schools deemed it too dangerous for gym class. The Rockville teenagers play the game like this: You get hit, you stand behind the players on the opposing team. You're back in if you hit one of them. A team loses when all its players are on the other side.

The sport has made a comeback, particularly among adults, thanks largely to last year's hit film "Dodgeball: A True Underdog Story."

It was after Ted Yegen saw the movie last summer that he decided to bring the game to Rockville. Through phone calls, e-mail and instant messaging, he got some of his neighbors and classmates at Walter Johnson High to meet at Tilden Woods Park, where the lighting allows for nighttime games. About 10 people showed up. As word spread, younger siblings, cousins and friends joined in.

"They were small games at first, and then it just got bigger," said Yegen, 19, who will attend the University of Vermont in the fall.

When school ended in June, the group decided to start playing again. Even some Walter Johnson High alumni who are home from college participate.

Often, the games spark the curiosity of passersby.

"What is this?" asked Nick Finelli, 19, on a recent Thursday night. He and his brother Phil, 17, were driving by when they saw the lights.

"Dodgeball," a sweaty Phillip Jasper said. He asked Finelli if he wanted to play. Finelli, home for the summer from The Citadel in South Carolina, declined.

"This is crazy," Finelli said, shaking his head.

The teenagers' parents don't think so. For them, the nighttime games are a welcome distraction from the trouble kids can get into on summer evenings.

"It gives them something to do that doesn't put them in a situation where they feel pressure to drink," said Bob Jasper, father of Phillip and Michael. "They're off the streets. They're in a group. They're safe."

Safe from everything but the ball.

Adam Parshall, a soon-to-be freshman at Georgetown Preparatory School in North Bethesda, hesitated to play because he thought that at 14, he was too small and young. But he learned to throw as hard as he can. And he learned not to take it too seriously. "It doesn't matter," he said. "I play the best I can."

When someone hurled a ball at him on a recent night, he lunged his hips forward and jumped out of the way. "You can't touch me!" he shouted triumphantly.

By 10:30 that night, they were down to 11 players, from a high of 40. They had lost count of how many games they had played. They were all sweaty and thirsty. Some were bruised. They walked off the court.

"We done?" a couple of them asked. They looked around. No one said anything for a few moments. The lights were dimming.

"You wanna play again?" said David Simms, 19, an Emory University student, asking the question that seemed to be on most of their minds.

"Yeah," they said in unison, and returned to the court for one more game before the lights went out.

David Simms, 19, shows no mercy in dodgeball at Tilden Woods Park. As many as 40 teenagers gather each night, often playing until 11 p.m.Players take a break between rounds on a tennis court at Tilden Woods Park, where the lighting makes night games possible.Teammates rally before a round of play. The Rockville dodgeball games started last summer, inspired by the comedic film "Dodgeball: A True Underdog Story."