They came in from East Hampton and Garden City, or spilled out in droves onto Atlantic Avenue from the LIRR, congregating in front of Barclays Center singing “Don’t Stop Believin’.”

Long Island made its exodus to Brooklyn to support the Islanders on Sunday night, and brought part of the Nassau Coliseum spirit with it.

“It was incredible,” Thomas Hickey said of the atmosphere. “I love our fans. I didn’t know it was going to be that good. We have a great new culture they seem to be developing here, and we real ly fed off of that today.”

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Yes, it was different. No, Barclays doesn’t shake the way the Coliseum used to, but fans Sunday night hardly seemed discouraged, and they were rewarded for their efforts in overtime as Hickey’s goal won it, 4-3.

“It [sounds] like the Coliseum,” said Patrick Casey, 31, of Williston Park. “I was actually surprised. I said to [his cousin, Casey Bice] when it first started, it sounded very much like last year. I think the fans did a good job.”

Bice, who at 13 already is a seasoned Islanders fan, attended the final game at the Coliseum and agreed. The duo stayed in the raucous Section 206 and “it’s very exciting,” she said. “I feel the people are very excited and it’s just fun.”

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There were the usual fluctuations — the dejected hush when the Florida Panthers appeared to go up 3-0 on a goal by Aaron Ekblad, the dizzy celebration when the goal was disallowed because of an offside, and the near pandemonium when Frans Nielsen tied the score at 3.

When Hickey scored the winning goal? Well, it was just like old times.

“It’s definitely going to be new, like everything else we’ve had to adjust to,” said Michael Schuerlein, who made the trip from East Hampton with his stepson, 8-year-old Tyler Hansen.

Schuerlein was about his stepson’s age when he went to his first Islanders game, and the two were going to have a sleepover at his dad’s house in Bethpage to make the trip a little bit more palatable.

“I think it’s going to be loud,” he said before the game. “I went to the game last Sunday against the Flyers and it was loud and exciting, even though we watched Bridgeport [the team played a number of its second-string players], basically, so I think it’s going to be loud.”

Brian Levkovich and his dad, Tobias, made it in from Woodmere. They were at the Coliseum for last year’s first-round matchup.

“I’m looking forward to people yelling and screaming and rooting on the Islanders,” said Brian, 21, who said fans are warming to the new home. “I think it took a little bit of time to get going. Probably had to do with the fact that people were getting used to the facility here . . . but ironically we ended up making more games here.”

Still, Barclays lacks the nostalgia and history of the no-frills Coliseum. Matt Stein, 26, a season-ticket holder, misses the days when he could jump up from the top row and touch the ceiling, or how his yells would reverberate across the walls. But he’s already renewed his tickets for next season and said he’s fully acclimated.

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“Noise traveled through that whole building,” said Stein, of North Bellmore. “But I love it here. Being here, being around here, I’ve made it my home. The Coliseum will always have the biggest piece of my heart, but this is home now and we’ve got to make the most out of it. We’re not going anywhere.”

The Islanders appreciated the loyalty.

“Our fans were very energetic, to say the least, and we wanted to make sure that we use that to our advantage, and I think tonight we did,” Travis Hamonic said. “[It was] 3-1 [Florida], the crowd was still going. It was rocking, and we felt like we had to keep pushing. Keep pushing.”