QuizUp, a Social Trivia App, Tests Mobile Gamers Every year, a new game craze captures the attention of mobile phone users around the nation and globe. This season, it seems to be QuizUp, a social trivia game for iOS devices. The game is a bit like playing "Jeopardy!" with friends, or strangers, if no one you know is using the game. People can challenge each other in a variety of topics, ranging from celebrity gossip, varieties of beers, Internet culture, history and science. Thor Fridriksson, the founder and chief executive of Plain Vanilla, the app development firm based in Reykjavik and San Francisco that released the game, said QuizUp's appeal has been "off the charts." The game, which was released in early November, has already attracted 5.5 million registered users. QuizUp users spend an average of 35 minutes a day playing the game, according to the company. Mr. Fridriksson said the success has been a surprise; the company started out trying to make educational games for children. "We naïvely assumed that really doing a good project would be enough to conquer the world and the app store," he said. That was a great misconception on our part, when I look at it in hindsight. The team released an educational app two years ago, but within a few short weeks, Mr. Fridriksson said, the company quickly realized "we were not going to break even." Short on cash and eager for a hit, he said, the developers switched gears and started brainstorming. They landed on the idea for a trivia game, sketched a prototype and started shopping it around to investors in Silicon Valley and New York. "There's so much noise and entrepreneurs with the next great idea," he said. I didn't realize how important it was to get the proper intro. I just cold-emailed to all of the big venture companies and said, "I have a game that will be the next big thing." " Mr. Fridriksson said that although his company didn't have a working version of the application it hoped to build, it could show off the educational app for children as an example of its capabilities. "Even though it was a failure, I think it was important to show what we had made," he said. In three months time, the team raised $1.2 million and started building out the application. In late December, the company raised an additional $22 million in a Series B round of funding. The company currently has no business model or plans to monetize the application anytime soon, but isn't worried about that for now. Mr. Fridriksson said he's especially buoyed by the popularity of the in-app discussion boards, where people chat about books and other topics, which are also heavily trafficked by users. "We're going to explore the platform further," he said. There is a kind of buzzworthiness there.