The more than 600 contestants are military veterans from across the country and from Britain. There is also a delegation of observers from South Korea.
Symons, who now lives in Austin, Texas, said he lost the use of his legs in a motorcycle accident in 2009.
"I laid in bed for a good while, almost a year and a half. Then I saw this sport and said, 'I gotta do it,' " Symons said.
He has competed in the wheelchair games the last three years, he said.
The games are put on by the U.S. Department of Veterans Affairs and the Paralyzed Veterans of America and will draw on the support of 2,500 volunteers.
This is the first time the games are being held in Philadelphia. Last year, they were in Tampa, Fla.
Mike Gallovcis, a VA official in Washington, said the games bolster the spirits of wheelchair-bound vets.
"Most people who serve in the military are fit, athletic and competitive," Gallovcis said. "And when they experience a life-changing injury, those traits are still with them. This event gives them a chance to be competitive."
Scot Severn, 46, of Caro, Mich., who was struck by lightning in 1989 while with the Army Reserve in Michigan, said playing "murder ball" was "just fun."
Severn, a large man who also competes in swimming, discus, and shot put, said he enjoys the rugged hitting involved in the sport.
"Sometimes we'll just intentionally hit for the hell of it to put on a show for the fans," Severn said.
Navy veteran Billy Ray Pearce, 45, of Barto, a small community in Berks County, was paralyzed by a combination of a spinal tumor and knee and back injuries.
A father of five, Pearce brought two of his sons to watch him compete in nine ball, swimming, and hand-cycling.
"This is my first time at the games," Pearce said. "This is all new to me. I'm excited and I'm proud to be here with all the athletes."
Competition will be held at the Convention Center, Thomas Paine Plaza, Liberty Bell Center, Martin Luther King Drive, and Kroc Center in Philadelphia and in New Jersey at Moorestown High School, Laurel Lanes, and Pine Valley Gun Club.
For a schedule of events and venues, go to www.pva.org.