No, your iPhone isn’t broken: The same game, Trivia Crack, is the top downloaded title on both the paid and free sections of Apple’s App Store in the U.S.

That’s highly unusual, since apps are usually either free(ish) to download or paid, but both the gratis version of the trivia game and a paid version have been on a crazy run lately. Since early in December 2014, Trivia Crack has been in or near the top 10 of all U.S. download charts on iOS and Android, according to App Annie; developer Etermax says the game is being downloaded 750,000 times per day in the U.S.

The app, originally launched in late 2013, is also making moolah at a pace that has eluded its chief competition, QuizUp. More on that in a minute.

For the unfamiliar, Trivia Crack works like this: Players compete to answer random questions in six categories — sports, history, science, geography, entertainment and art. Get enough right, and they collect cartoony characters for each category (sort of like Trivial Pursuit’s wedges). All the questions are submitted and moderated by other users.

There are about one million “active” questions in Trivia Crack’s system, Etermax CEO Maximo Cavazzani said in an interview with Re/code. The other 50 million questions submitted to date are “inactive” because they’re either awaiting moderation or have been rejected by the game’s users for being non-substantive, not fun or just offensive.

“Many of those questions are just garbage,” Cavazzani said.

For example, one user recently tried to submit a question asking how many people the Nazis killed. The user’s “correct” answer was “not enough.”

“That question would never reach the production level,” the CEO said. About 2,000 new questions do reach that level and are added to the game every day, according to an Etermax press release.

Users can volunteer to translate questions from one language to another, although Cavazzani stressed the importance of localizing question sets for different countries. Players in French Canada and France find different topics fun, and players throughout Latin America want to see their own individual cultures represented, he said.

“Argentinians and Mexicans have the same language, but they don’t have the same interests,” Cavazzani said. “People will have fun for a little while, but if they don’t see their movie stars or things that relate to them, they won’t feel the game is their own.”

After it convinces players to come back for more, Trivia Crack makes money in a couple of interesting ways.

First up are ads, either the revenue from displaying them in the free game, or from sales of the $3 ad-free version; Cavazzani estimated, however, that only one percent of users had downloaded the paid app. Like many other games, it also has a virtual economy, awarding users coins that can buy power-ups to skip questions or make them easier.

Since its U.S. downloads began climbing late last year, Trivia Crack’s economy has made it a top-20 grossing app on both iPhones and Android devices, per App Annie; at its peak in late 2013, competitor QuizUp reached No. 228 on iOS and 453 on Android. In fairness, though, QuizUp puts far less emphasis on its store than Trivia Crack, selling only a few non-essential items.

Update: I emailed QuizUp last week about its other monetization practices and heard back this morning: While most of its daily featured quiz categories are chosen by the quiz editors, QuizUp maker Plain Vanilla Games has made and promoted sponsored quizzes “every now and then,” with clients including Disney, Coca-Cola, Google, the Smithsonian and the History Channel. Plain Vanilla CEO Thor Fridriksson said the company is testing other monetization methods, but wants to avoid being “pushy.”

Etermax’s Argentina-based team of 18 80 is currently working on ways to beef up its economy even more, looking for inspiration to GungHo’s Puzzle and Dragons. Cavazzani said players will be able to use coins to buy collectible characters, like the titular dragons in GungHo’s game, that give them special permanent boosts like reloading lives or earning new coins faster.