The loud popping sound of orange-tipped M4 airsoft rifles rang out.
Somewhere close by, Cody Pamula, 14, kept still with his back to the wall.
All around, men and boys of all ages -- faces obscured by masks -- ran, dodged and dived between plywood walls, industrial barrels and the kind of fake plants commonly found in office waiting rooms.
Someone peeked out of a nearby window cutout, only to jerk his head back quickly before a swarm of bullets hit the wall with loud "thwacks."
Pamula braced himself and sprinted across the field, shooting as he went.
Then he felt a sharp sting. He'd been shot.
Like all the other players in the Erie Airsoft arena who had been tagged, he simply raised his airsoft gun in the air and walked, yelling "Dead man walking," while the rest of the players finished the game.
Airsoft is a combat sport that uses small, round plastic pellets, or BBs, shot from realistic-looking guns. In the last decade, the sport has gained momentum in Asia and Europe.
Erie Airsoft -- located in Forward Hall, 2502 Peach St. -- is advertised as the area's first commercial arena for the sport that's now gaining popularity in the United States.
"When we started, we had one to 10 kids come in on a weekend," said Chris Gerhart, founder and co-owner of Erie Airsoft, which opened after Christmas in 2009. "Now we have about 40. There's just been a lot of enthusiasm.
"It's very affordable," he added. "That's a big plus with this economy."
The floor above Forward Hall's performance space is a kind of war-torn urbanscape that might be found in the virtual worlds of "Call of Duty" or "Fallout" video games.
For $10 each, players can run for six hours in an arena of plywood buildings, stacks of tires and barrels playing airsoft.
In the showroom outside the arena, players can rent any of the airsoft guns and airsoft protective padding displayed on the walls and in glass counter cases.
But as far as strategy goes, players are on their own.
"There are no limitations. You can run, crouch, hide -- do whatever you can to survive," Gerhart said. "It's fascinating to watch a group of 12-year-olds come up with a battle plan."
Injury is a reality, which is why players are required to wear protective masks that cover their eyes and ears, and other padding. Despite the orange tip that marks these replica airsoft guns as fake, they're used as though they were real.
Signs close to the airsoft arena list the rules of the game and a disclaimer: "By entering, you will be responsible for any risks or loss or injury!!!"
"Every sport has inherent danger, and we try to minimize that as much as possible. Treat the Airsoft guns as if they were real guns. It can't be stated enough -- we do a lot of airsoft safety briefing," said Gerhart, who served in Iraq from January 2004 to May 2005.
"Players often have a greater respect for weapons safety after they handle Airsoft rifles," he said.=
Behind a large door is the close-quarter battlefield, crude plywood buildings with painted-on bricks or simply graffiti. The only illumination comes from Christmas lights lining parts of the buildings, casting an eerie glow on the entire scene.
As you walk, stray BBs from past battles are kicked up and sent scurrying across the floor.
"Players like it rough looking. They like it looking like a battlefield," Gerhart said. "This is the physical, real world version of a first-person shooter."
Renovations for a second arena in the basement are already underway, which will add about 500 square feet of new airsoft arena space. While the current upstairs arena can accommodate about 40-50 airsoft players at a time, the new addition will allow for a total of about 75-80 airsoft players.
The new arena, which will be connected to the upstairs arena, will be available to players in about a week, Gerhart said.
As word-of-mouth spreads and signs are posted around the city, more players are showing up each weekend. Pamula discovered Airsoft when a friend had a birthday party at the arena a few months ago. Now he's there most weekends.
"I tried it out and I loved it," he said. "It's just a lot of fun to play with your friends."
On a recent weekend, Pamula came with a group of about 20 people -- including his father, Jay Pamula, 36, who is quickly becoming a fan of the game.
The challenge and strategy needed to play the game -- which also can be used for military training -- adds a level of excitement that can't be found in a video game.
"It's not a game where you put in a quarter every time," Cody Pamula said. "With a video game, you're on your living room couch. Here you're moving, you're breathing heavy and diving around corners."
Although there are safety concerns with Airsoft, Jay Pamula said he likes the indoor setting that's closely monitored by employees.
"I'd rather him play here than on the streets or in the woods where no one is watching and keeping airsoft safety in mind," he said.
Jay Pamula, a staff sergeant with the U.S. Army Reserves, also served in Iraq. The combat style of Airsoft allows for a more realistic experience than paintball.
The biggest threats aren't the big and burly former servicemen in the arena. It's most likely Toby Charlton, a quick and slight 7-year-old who stands only a few feet tall.
His strategy: "Stay in one spot and shoot."
His brother, Tyler Charlton, 8, has the opposite approach: "I'm usually the one who goes 'Let's go, let's go!' You have to get them before they get you. It's really exciting."
Flushed from the excitement of a recent battle, Tyler already has made plans to come back for his birthday party on March 29.