FORTUNE — You’ve heard the cliché a million times: Gaming is a hits-driven business. Just ask our friends at Zynga (ZNGA), which rode Farmville, and then CityVille, to an IPO and subsequent collapse. Or OMGPop, whose hit app Draw Something lost millions of users just as fast as it acquired them (but not before selling to Zynga for $200 million). Or Rovio, which had to make its hit Angry Birds games free in recent months to keep users interested in the aging franchise. Search trends even show a waning interest in Candy Crush, the hit of 2012 whose parent company has filed to go public later this year.

Gamers, especially casual gamers, are a fickle bunch.

That’s why the staying power of QuizUp, a social media-enabled trivia game that hasn’t left the top of the Apple (AAPL) App Store Rankings since it launched four months ago, all the more impressive. Four months isn’t terribly long, but in app time, it’s ages. As I wrote last month, hot social networking app Secret became the latest in a line of faddish apps, and we’re burning through fads faster than ever. Just two months after its launch, Secret has begun to decline in App Store rankings, according to ranking service App Annie.

“Games usually have a very, very short life cycle, where if they break on through, they will get super-popular for a couple of days, then they hit a cliff. In a week or so they just plummet off of the top 100,” says Thor Fridriksson, CEO of QuizUp’s parent company, Plain Vanilla Games. “We have seen so many games come and go like that while we were hanging in there.”

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In just four months, QuizUp hit 10 million registered users who spend an average of 30 minutes per day playing the game. That includes people who’ve only played it once, which shows just how much the top users — who have played tens of thousands of rounds of trivia, are engaging.

QuizUp has maintained its position in the top 25 game apps and top 50 or so overall apps in the U.S. Market. In that time, the company has grown from seven to 45 employees and raised a big $22 million round of venture funding from Sequoia Capital, Tencent, Greycroft Partners, BOLDstart Ventures, and e.ventures. The company recently partnered with talent agency WME to develop QuizUp-branded content for other channels, like TV.

QuizUp was a hit from the moment it launched in the App Store. Fridriksson says it’s a result of years of tweaking and perfecting the game. That method runs counter to the popular “lean startup” methodology of launching an imperfect product and iterating on it based on user behavior. The “done is better than perfect” philosophy did not apply with QuizUp, and perfectionism almost killed the game. Two years ago, Fridriksson was living in Iceland (where he was born) and bankrupt. He’d published one title, and it was a total failure.

But he persisted with the trivia app idea, launching eight different quiz apps to test out user behavior. That way when QuizUp finally did launch, it was fully optimized. Fridriksson attributes QuizUp’s success to his company’s “abnormally long development cycle.”

“When people talk about overnight successes, QuizUp kind of was when we launched in November, he says. But it was two years in the making.”

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Since the launch, the company has been on a sprint to keep up. For the first month, the team struggled to keep servers afloat. Then they were busy raising money and scaling up the team. Then they expanded QuizUp’s trivia offerings from 150 topics to 420 topics. (A recent new category around the movie Mean Girls has surged in popularity.) The latest update, announced today, brings the game to Android devices.

QuizUp’s next move will be to expand internationally. Since trivia is tied to culture and can be very local, the company has held back on international launches in non-English speaking countries.

In the U.K., where QuizUp has topped the App Store charts, users have given the app lower ratings because the content is too Americanized. QuizUp recently introduced more questions on the royal family and the X-Factor U.K., which users quickly embraced, says Fridriksson. The company will hire local teams to introduce relevant content for each new region, he says.

Fridriksson says the last four months have felt “a bit unreal,” since the kind of funding and valuation numbers his company have garnered are unheard-of in Iceland. “I hope to inspire future entrepreneurs from the Nordics that you can just go to America and get lucky,” he says. “Fortune favors the bold and all that.”