Sitting in church services on a Sunday morning last month, Julia Harryman noticed that her husband was playing the quiz game “Trivia Crack” on his phone.

“I just looked at him and smirked,” says the 45-year-old mother of two from Dallas, who admits that she’s also hooked on the game and doesn’t blame her husband for sneaking in a move. “Sometimes you just can’t help yourself.”

Trivia Crack is the latest red-hot mobile game. It has been downloaded more than 130 million times. For 66-straight days, it was the most popular free download in Apple Inc. ’s U.S. app store, ahead of the likes of Facebook Messenger, YouTube and Snapchat.

That’s a streak far longer than those held by previous chart-topping games such as “Candy Crush Saga,” according to analytics provider AppData. The free version of the original “Angry Birds” never cracked the No. 1 spot.

Though the object of Trivia Crack is far from novel—players compete to correctly answer questions first in categories such as sports, art and science—a key distinction is that the game features mostly questions written by players, along with their names and photos.

Now, though, that standout feature is starting to backfire.

Etermax, the small Buenos Aires firm that makes the app, is struggling to keep up. In recent months players have been submitting an average of one million questions a day to Trivia Crack’s “Question Factory,” a section within the app, says its 29-year-old founder and chief executive, Maximo Cavazzani. Since each submission must get a positive rating from at least 100 fellow players to make the cut, only about 1,500 new questions are being added to the game each day.

“It’s a problem we haven’t dealt with,” the entrepreneur says. “It’s like building a house and a million people came to help you. We just need one house.”

Also bogging down the review process is a consistent glut of questions that are basically the same but posed in slightly different ways. For instance, the game on a daily basis receives multiple versions of “How old is Justin Bieber?”

Mr. Cavazzani says that allowing players to review submissions, as well as rate already published questions as “boring” or “fun,” is what keeps the game’s content fresh and entertaining. It means most players shouldn’t see inaccurate or offensive material or have to roll their eyes at corny castoffs such as: “Who’s never gonna give you up, never gonna let you down, never gonna run around, or desert you?” (Answer: Rick Astley)

The backlog of submitted questions awaiting approval is starting to irk some Trivia Crack fans. Chuck Monsanto, of Yonkers, N.Y., likes to play the game while riding the train to and from work. The 47-year-old fraud investigator says he sent four questions to Trivia Crack last month that he thinks are top notch, including: “What was the title for Led Zeppelin’s fourth album?” (Correct answer: It didn’t have a name.) He’s stumped as to why the questions haven’t yet gotten enough “likes” from other players. “You see these really goofy questions and wonder how those get approved,” he says.

Trivia Crack’s 66-day stretch at the top of Apple’s free download chart is nearly double the 36 consecutive days for “Draw Something” in 2012, says AppData. The longest streak at No. 1 for “Candy Crush Saga” was just five days.

But among top grossing apps, Trivia Crack is currently No. 17, while “Candy Crush Saga” ranks third, trailing only “Game of War--Fire Age” and the leader, “Clash of Clans.”

Etermax, which has six mobile games including Trivia Crack, is “very profitable,” says Mr. Cavazzani, declining to provide specifics. Trivia Crack generates most of its revenue from in-app purchases and advertising. Since it was first released in October 2013, fewer than 1% of its players have paid for the $2.99 version that eliminates ads. In addition to Apple iOS devices, the game can be played on mobile products from Google Inc., Microsoft Corp. and Amazon Inc., as well as Facebook.

Mr. Cavazzani says he intends to double his company’s 80-person staff this year and that a sequel to Trivia Crack is planned for the spring with more ways for players to contribute questions. The game, available in 10 languages including Catalan and Dutch, has already been adapted into a TV quiz show in Latin America, and fans can find T-shirts, mugs, pillows and other items with images from it for sale online.

“It’s not the first trivia game in the world, but it’s the best,” says Mr. Cavazzani, whose company developed finance apps before switching to games in 2011. He says it took years to perfect the game’s design, social-connectivity and user-input combination.

“No one can do a great game if you started yesterday. It’s a long path of learning,” he says.

A company with a hit app on its hands isn’t guaranteed future success. Zynga Inc. hasn’t come close to replicating the success of early hits like “FarmVille” and “Words With Friends.” Rovio Entertainment Ltd. has struggled to branch out beyond “Angry Birds.” Even King Digital Entertainment PLC’s Candy Crush sequel, “Candy Crush Soda Saga,” spent only a few days at the top of the free-download charts.

Mubarak “Mo” Ahmed, a 36-year-old financial analyst from Edison, N.J., says his interest in mobile games comes and goes. For instance, he used to play “Words With Friends” regularly, but eventually, he says, he “got bored” with it. He’s now playing a lot of Trivia Crack, juggling about eight games at a time. “Most of these mobile games are pretty faddy,” he says. “Unless they keep changing, they get old. You get tired of the monotony.”

TV quiz shows date back to the 1940s, but trivia games didn’t become a pop-culture sensation until four decades later when “Trivial Pursuit,” one of the first board games to be marketed to adults, arrived in the U.S. from Canada, says toy historian Tim Walsh.

For Dave Levy, a Chicago emergency-room aide who plays Trivia Crack multiple times a day against colleagues, the authenticity of the questions is a major plus. “‘Trivial Pursuit’ seemed to be influenced by what a major corporation wanted people to see,” says Mr. Levy, 34 years old, while Trivia Crack feels current. “If something happens in the media or if there’s a new show or book out, I might see a question about it," he says.

Finding a way to reduce the number of new questions awaiting review may be tough for Mr. Cavazzani’s Etermax. It already provides an incentive for players to rate submissions in the form of free virtual coins they can use to buy “power-ups,” such as an extra 15 seconds to answer a question or the option to remove two incorrect answers.

Ms. Harryman, the player from Dallas, who runs a technology firm with her husband, is eager to find out if seven questions she submitted in December will make the grade. One of her favorites: “Which rock star turned down knighthood for political reasons?” (Answer: John Lennon)

“You put a lot of thought into the questions, because you love the game so much,” she says. “[But] if they don’t start updating it, it’s probably going to get too repetitive.”

This article was originally published on 20-02-2015 on The Wall Street Journal

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