There is a popular new trend hitting smartphones nationwide: mobile trivia apps. Over the past year, developers have created a wave of mobile trivia games where users compete for real money by answering questions on their smartphones. Millions of people are playing against each other on these apps every week.

One of the most popular mobile trivia apps available today is HQ Trivia. Over 2 million people played to win part of the HQ Trivia $250,000 prize pool last week. It was HQ Trivia’s biggest prize ever as well as a record number of players for one of its games.

Rus Yusupov and Colin Kroll, the founders of Vine, cofounded Intermedia Labs, HQ Trivia’s parent company, after experimenting with an interactive live-streaming video app. The live game show app has become a cultural phenomenon. The show now airs every night at 9 p.m. EST and at 3 p.m. on weekdays on the trivia game’s app.

The premise of HQ Trivia is simple. The players must answer 12 increasingly difficult multiple-choice questions to win any money. They get 10 seconds to answer each question. Players that answer correctly are allowed to proceed to the next question, while those who answer incorrectly are eliminated. The winners split the prize equally.

HQ Trivia makes it money through advertising and sponsorship. The $250,000 prize pool was sponsored by Warner Brothers as a promotional stunt for its new movie “Ready Player One.” A previous $100,000 prize pool was sponsored by Nike. The four winners in that game were also each awarded a pair of special-edition HQ Air Maxes.

HQ Trivia has several regular presenters in its rotation, but stand-up comic Scott Rogowsky is its most frequently used host. His credits include the ABC hidden-camera reality show Would You Fall for That? and the live talk show Running Late. HQ has rocketed him on an untraveled career trajectory. Rogowsky said in an interview, “I’m so fortunate to be the pioneer in this, to be the first to get this kind of job.”

A whole new generation of trivia fans is being created by these apps. Trivia games can now be a profitable hobby for anyone with a smartphone. There are a half dozen mobile trivia apps available to download today. An app called Prove It has a slightly different model than HQ Trivia. With Prove It, users bet money against other players.

Your competition on these mobile trivia apps could be anyone. Legendary news anchor Dan Rather won HQ with his family on Christmas Eve. Investors are paying more attention to these apps too, now that the medium has a proven audience.

The company behind HQ Trivia recently secured a $15 million investment from Founders Fund, a venture capital firm co-founded by tech entrepreneur Peter Thiel. Yusupov said, “We’re incredibly grateful to have the backing of Founders Fund. They’re one of the top venture firms in Silicon Valley.”