Pokemon Go Fest or Pokemon Go Fail in Chicago? Getty Images

Niantic promised a “legendary” experience for this weekend’s first-ever Pokemon Go Fest in Chicago, but Wi-Fi problems and long wait lines derailed the event as thousands of players were issued ticket refunds.

The gaming event Saturday in Chicago’s Grant Park had seen nearly 20,000 attendees lining up to get in the entrance as early as 6 a.m. The tickets they were there to purchase sold out in less than 10 minutes, while skyrocketing prices online soared as high as $450 on eBay and other sites.

But the thousands of Pokemon trainers who traveled to Chicago for the augmented-reality smartphone game immediately took to Twitter to complain about Wi-Fi connectivity issues and app glitches. By 1:30 p.m., Niantic Chief Marketing Officer Mike Quigley announced there would be refunds of the original $20 ticket cost in addition to $100 of in-game credits, the Chicago Tribune first reported.

Read: Niantic Confirms Legendary Pokemon Go To Appear In New Updates, Chicago Festival

“Obviously, today has not gone as planned,” Quigley told reporters after the announcement. “It has been a really unfortunate situation.”

"Today at Pokemon GO Fest in Chicago, technical issues created problems for a large number of players attending the event," a Niantic spokesperson said in a statement. "From everyone at Niantic, we apologize to all of the Trainers who came out to Pokemon GO Fest today. Although we were able to solve many of the technical issues, we were not able to offer every attendee a great experience."

Discontent continued at the festival, the first of several worldwide Pokemon Go events this summer that have been organized in celebration of the mobile game’s one-year anniversary. Boos, thrown bottles and bad attitudes showed up in Twitter reactions throughout the day.

While many attendees blamed internal app glitches some also blamed poor internet connectivity and phone carrier service.

"Almost everyone on the festival grounds who didn't have Sprint as a provider was unable to log in to the game," said Brandon Omernik, 23, in a discussion with CNN.

The crowd booed several Niantic officials, including when founder and CEO John Hanke took to the stage to address the crowd. “We can’t play” and “fix the game” chants interrupted his comments as festival-goers ridiculed the game as unplayable.

“I know that some of you guys have had trouble getting logged on this morning, and I wanted to let you know that we’re working with the cell companies—AT&T, Sprint, Verizon, trying to get that worked out,” Hanke said, amid heckling from frustrated trainers. “And we’re working on the game server to get that worked out. So, I want to ask you guys, please know, we’ve got the whole Niantic team working against this, so please be patient with us.”

Chicago organizers had hyped the event for weeks because of attendees’ ability to “unlock” in-game bonuses and even see the unveiling of the first-ever “Legendary Pokemon.”

"On July 22, thousands of Trainers in Grant Park for Pokemon Go Fest and the millions of others around the world will be working together to unlock in-game bonuses for the entire Pokémon GO community," according to a post from the official Pokemon Go page earlier this month. "If they manage to catch enough Pokemon during the Pokemon Go Fest Challenge Windows, the first Legendary Pokemon will be revealed in Grant Park. If the Trainers in Chicago succeed in defeating the Legendary Pokemon, that Pokemon will start appearing in Raid Battles around the world, after Pokemon Go Fest."

And while it was technical difficulties that deflated Niantic’s grand Pokemon plans, it wasn’t for the reason many organizers had warned: the weather.

"I was still happy to meet so many awesome people playing the game however and the weather was perfect," Omernik told CNN.

The Pokemon Go organizers took to Saturday to inform attendees that that all those who registered to attend the Chicago event will have the Legendary Pokemon, Lugia, added to their account anyway.