Fans walk on the warning track at Fenway Park  before the resumption of a suspended game between the Red Sox and Royals. Children under 18 were allowed to attend for free. Michael Dwyer/Associated Press

BOSTON — The game still counted in the standings, but the environment Thursday afternoon at Fenway Park was unlike anything the Boston Red Sox have seen before.

With dollar hot dogs, largely reduced food prices and free tickets for children while adults could gain entry with just a $5 donation to the Jimmy Fund, the century-old ballpark was filled with people who might not otherwise get a chance to watch the most expensive team in baseball at one of the most expensive venues.

“It was one of the coolest atmospheres that we’ve had here,” said Brock Holt, who hit a walkoff single 12 minutes into the suspended game to capture a 5-4 win over the Royals. “Just how many people showed up and how excited they were. The music was loud pregame and everyone was dancing and seemed to be into the game.”

Watching all the children fill the park was such a success Thursday that Red Sox President Sam Kennedy was feeling confident the club one day soon could introduce an “open house day,” when kids enter free for select games on a regular basis.

“Could we have an open house day, where we put aside 10,000 to 15,000 tickets just for kids on an ongoing basis free of charge? The obvious answer is yes,” Kennedy said. “There’s a market for that. We need to challenge ourselves to see if that could be a possibility. We’ve talked about that. On lower demand games you might have an opportunity to do that. It really is an investment in the future.”

There were more than 16,000 folks who entered the gates (including upwards of 6,000 free tickets for children), leaving the 37,000-capacity park almost half-full with an open-seating arrangement providing a unique backdrop for players on the field.

“To me, the best crowd we had the whole year,” third-base coach Carlos Febles said. “They were into the game. They were loud. That’s what you need. That’s one of the reasons the guys said, ‘Let’s do this and get out of here.'”

The result was a gleeful afternoon of baseball that was over in a hurry.

“That’s what it’s all about,” said Manager Alex Cora. “We’ve got to do everything possible to get the young fans involved in this beautiful game. That was fun.”

Children were allowed to walk on the warning track before the game, something Josh Taylor noticed while he was warming in the bullpen.

“It was cool to see the kids on the field enjoying the experience,” Taylor said.

It was such a successful afternoon that the Red Sox were “flying high over it” in the front office afterward, Kennedy said.

Like every MLB team, the Red Sox have been desperate to generate interest in a younger audience and build the next generation of loyal fans. Watching so many flock to the gates for a suspended game against one of MLB’s worst team reminded them that providing inexpensive opportunities is the best way to get families in the park.

“I’ve never ever seen such a young group,” Kennedy said.” We have a lot of kids come to Fenway but it was all really young kids. There’s a big takeaway, which is young fans and families really want to be at Fenway. They support us all year long but when you have a chance to do something like today, you need to do it.”

The Red Sox have already been thrilled with the results of their student ticket initiative, which provides a sizeable allotment of $9 tickets to students for each game.

“We see days like today as an investment into the future,” Kennedy said. “It’s not lost revenue or an expense or anything like that. It really is an investment.

“One thing we thought about for years is, can you do more with kids? We always push ourselves. We’ve got the big concourse, all the activities, the $9 student tickets, a huge initiative for us. We’ve seen a lot of growth.”

The obvious follow-up question is this: how do you create a product on the field that connects with the younger generation?

The Red Sox play the longest games in MLB, averaging 3 hours, 23 minutes per game. Thursday’s game was over in 12 minutes, but including the first nine innings that were played on Aug. 7, the game lasted 3 hours, 48 minutes.

“For those kids, it’s probably their first big league inning,” Cora said. “That’s what they’re going to remember. But we’ve got to remind them that this is not the pace we play. Usually we play 4-hour games.”

The pace of play is such a problem that Holt, an eight-year veteran of the game, said he doesn’t even like to bring his son, Griffin, to the ballpark.

“I mean, I don’t know what we can do,” Holt said. “Baseball is kind of a hard thing for kids to get into. Games are long and kids’ attention spans aren’t. So as a parent I’m not trying to bring my kid to a nine inning, 4-hour game. But today was fun. Today was fun. For them to kind of think of what they did today, kids get in free and lower the ticket prices and stuff, it was cool.”

Now the Red Sox will try to figure out how to replicate the atmosphere on a more regular basis.

“We need to be in the long term business,” Kennedy said. “We know that if we don’t make days like today available, or $9 tickets available, or have great wifi or connectivity through your cell phone signal, we’re in big trouble. We have to make the experience and product enjoyable and accessible to kids. That’s a huge part of what we’re doing here.”