The lights went dark before the game at the Barclays Arena on Tuesday night. A glossily produced video blared from the video screens, filling the 19,000-seat venue with sound and clips of Nets dunking or shooting through colored wisps of smoke, along with the words “Brooklyn Together.” Then the team’s starting lineup sprinted onto the court, one by one, as they were introduced by the public address announcer. And with each name, the crowd roared.

Well, it was a fake crowd mostly — piped in through the speaker system — that provided the roars as the Nets got set to play the Sacramento Kings. The actual crowd in attendance — about 300 or so — mostly sat quietly in their seats, lightly clapping as if they were watching a Dvorak symphony or a middle school graduation.

Tuesday night was the first time that the Nets allowed fans to watch a game in person since March 8 of last year, when more than 15,000 people attended. Two weeks ago, Gov. Andrew M. Cuomo announced that venues with 10,000 or more seats would be allowed to host fans at 10 percent of the venue’s capacity.

Barclays could have hosted thousands more fans, but opted to start small. To attend, patrons had to take two coronavirus tests — one within 72 hours of the game and another, rapid version on site.

Across New York’s East River, similar scenes were playing out when the Knicks hosted the Golden State Warriors at Madison Square Garden. The crowd was a bit bigger in Manhattan — about 2,000 fans — but it was enough that Knicks Coach Tom Thibodeau called the night “a first step back toward normalcy.”

The Knicks boasted the game had been a “sellout,” and before it began the fans chanted “M-V-P! M-V-P!” and nearly drowned out the remarks of Julius Randle, who addressed the crowd after being named the Knicks’ first All-Star Game since 2018. By the second half, even the visitors got a sense nature was healing. The Warriors won, 114-106.

“There were some fans heckling,” Warriors guard Stephen Curry told reporters after the game, “which was awesome.”

The Nets and the Knicks are two of 14 N.B.A. teams allowing patrons to attend games in some way.

“It’s a nice change,” Nets Coach Steve Nash said. “We obviously have been playing in empty stadiums for the most part, at least at home. And so to have some fans and a little bit of life and energy, and hopefully we can safely incorporate more fans as we go here.”

Barclays Center was a microcosm of the disruption that the world has gone through over the last year. At times, it felt like an uneasy blend between a haunted house and a private Beyoncé concert. Thousands of seats remained unavailable, many still covered by tarps. Almost all of the arena’s restaurants were closed.

There was no line for bathrooms, and inside them some sinks had tape over them to encourage social distancing. A sign outside the arena, where scalpers used to roam, offered free testing for the coronavirus, the specter of which was never far away: After walking inside for the game, patrons were greeted with a warning sign that included the line, “Traveling to and from, visiting, and/or providing services in and around the arena may lead to a risk of exposure to COVID-19.”

Dozens of ushers stood idly by — back to work for the first time all season — holding placards shaped like stop signs that read, “Please wear your masks.” One remarked that while it was good to be back, she was befuddled by the lack of hallway traffic. “So why am I here?” she said. “There’s no guests!”

But as the Knicks’ Thibodeau noted across the river, Tuesday night also represented the first tentative steps back to normalcy in New York sports. Along with the ushers came the return of the Brooklynettes, the Nets’ dance team, and the team’s drum line. Before tipoff, a woman with a headset approached the rehearsing dancers, who were on an elevated podium far from the court, and pleaded: “We have to be really on it with our masks. Please.”

One drummer yelled across the arena — possibly to a team of breakdancers — “You all look wack over there.” In previous years, his voice would not have carried so far.

Shortly before tipoff, the Nets debuted a video of players speaking the lyrics to the Bill Withers classic, “Ain’t No Sunshine,” dedicated to absent fans. Then Kyrie Irving waved to the crowd on both sides of the court; in an arena with hundreds instead of thousands of people, fans might have been forgiven for thinking Irving was waving to them individually.

“It felt like you were sitting in your living room,” said Dylan Schultz, 27. “I’m sitting just with my friend. Not too many people around me. But there’s still this environment of the game is right directly in front of you. You could hear them talking to each other. Sick.”

Some in the building tried to keep up traditions, like trying to interrupt opponent’s free-throw shooting. On Tuesday, that effort — normally taken up by thousands of fans screaming and waving objects — fell to four drummers behind the basket, joined occasionally by the five dancers. (Statistically speaking, they could claim success: The Kings shot 13 of 19 from the line, slightly below their season average.)

As far as the game itself, the Nets led most of it and won their seventh straight, 127-118. Bruce Brown, the starting guard, got a rare turn in the spotlight, scoring 29 points, as did James Harden, who had a triple-double: 29 points, 11 rebounds and 14 assists.

For the most part, the crowd — scattered throughout courtside seats, luxury suites and some in the lower level — stayed subdued, in spite of having the most hyped Nets team in years to watch in person.

“It feels like you’re watching a practice session,” said Rich Schaefer, 42, a season-ticket holder. “You’re at a high school gym, and there’s no one there. But you’re watching the best players in the world. It’s not the same energy you get during sold-out games. But there is something incredible, as a basketball fan, of watching and hearing everybody talking and not being distracted by what’s happening around you.”

But for the players, the sight of friendly jerseys was a welcome one.

“Just having somebody in there to cheer you on is better than nothing,” Nets guard Joe Harris said. “It was definitely nice, even though 300 is not a lot in the big arena. But it’s still a better feel than the empty ones.”