Gamers play at tables set up at the convention. The Video Game United Conference was held on Saturday, August 16 and Sunday August, 17 at the Washington Convention Center in Washington, D.C. (Sarah L. Voisin/The Washington Post)

From the start, the plan was to go big, or go home. They just didn’t expect that this was how going big — putting their lives on hold and investing $100,000 of their own money — would turn out.

The two organizers of this past weekend’s Video Gamers United convention spent a year and a half planning and spending to bring a full-scale video-game convention to the District. Although the city isn’t known for its gaming culture, gatherings for comics and pop culture have done well here. So when Cesar Diaz, a Department of Defense employee whose wife loves “Call of Duty,” approached Curtis Smith, a corporate-sponsorship consultant, the idea seemed like a no-brainer. It was a space in the market, Smith said.

And in the days before the convention began, that was still how it seemed.

Oh, “25,000 people,” Smith said, on how many attendees he was expecting for the weekend. Area conventions similar to his VGU-Con have drawn as many as 50,000. “We know our demographic is big.”

For $75, attendees would get into the Walter E. Washington Convention Center for two days, where they could play video games, talk to video-game creators, listen to panels on the future of video games, listen to a concert of the music of video games, and compete in video-game tournaments with prizes up to $10,000. Hand-held games, console games, even vintage games by makers such as Atari.

Cesar Diaz, 34, is a CEO and organizer of the Video Game United Conference. (Sarah L. Voisin/The Washington Post)

The gamers would come.

It didn’t seem to matter that the Pokemon World Championship would be in the convention center the same weekend. Pokemon — with a loyal following around the world who would get free admission to see the planet’s best Pokemon players competing against one another — wouldn’t be a distraction, Smith and Diaz thought.

They paid for Metro advertisements, a professionally designed Web site and $80,000 in draping and signage. They had sponsorships from CBS Radio, the Nationals, Uber and four branches of the military. They had investors. They paid $8,000 for a two-story-tall Donkey Kong replica that was custom-made.

The gamers would come.

Diaz missed a few weekends of duty for the National Guard. He was toiling into the night after working his day job, while his wife ran the video-game arcade they owned in the Annapolis Mall.

She had started to call the convention “our child.”

“It’s going good,” he said Saturday morning, an hour after doors opened at 10.

Attendees play a large row of retro video games. (Sarah L. Voisin/The Washington Post)

The main hall had people milling about, but it was difficult to tell how many, because they were so spread out in the room, which was the size of three football fields. A security guard standing at the side of the room estimated he had seen 300 people.

There was an entire room for at-the-door registration, with poles and ropes marking enough space for hundreds of people to wait in line. Only four people were in it.

The gamers were coming, but slowly. And sparsely.

Instead of 25,000, Smith eventually had a new expected attendance: 7,000.

As Diaz walked through the convention hall, he could see joy on people’s faces. A middle-aged man playing an Atari game. A mom and her son climbing on a jet brought by the Air Force. A developer showing off his homemade video game at his booth.

This is what he had imagined, Diaz said. He had just pictured it more crowded. His walkie-talkie was squawking every few minutes. “Putting out fires,” he said. The sign company was trying to charge the vendors. The movie was starting, and no one had announced it. A gamer had come to play “Madden” at the time listed on the Web site, but they had decided to start the tournament an hour earlier.

“I just want a refund, man,” the gamer said.

Worried that the registration table wouldn’t be able to handle the request, Diaz walked the ­gamer to an ATM and handed him cash.

“Maybe what we should do,” Diaz said to his wife, Evie, soon after, “is have the cosplayers go upstairs to Pokemon and hand out these fliers.”

Cosplayers are people who dress in the costumes of specific characters, sometimes from video games. Evie looked skeptical. Diaz was called away on another fire.

By 1 p.m., registration was at 600 people.

At 2 p.m., some of the booths were still unmanned. Only a dozen people were paying attention to the celebrity gaming contest — one of the headlining events.

“These guys were shooting for the moon,” said Chris Totten, a game developer who created “Dead Man’s Trail,” a zombie spin-off of “Oregon Trail.” “Really, for a first-time convention, they’re doing very well.”

VGU-Con organizers said they had 7,736 registrants. They hadn’t added up the numbers by Sunday evening, but they knew they hadn’t broke even financially.

Maybe the $8,000 Donkey Kong wasn’t the best idea, they acknowledged. The convention’s materials had to be moved out by Tuesday, and they weren’t sure where they were going to store the giant gorilla, Diaz said.

They could save it for next year. Even though they had lost money, they said, there would be a next year.

“I think,” Diaz said, “we can go bigger.”