QuizUp

QuizUp built its identity on a single promise — an instant real-time duel against a random opponent from anywhere in the world on a topic you chose, ranging from movies and history to narrowly focused categories like a specific TV show or sports club. Both sides received the same questions at the same time, and speed as well as accuracy of answers decided the winner, creating a tension that turn-based quizzes like Trivia Crack didn't offer, which made the game feel closer to an online duel than a classic questionnaire.

The game was released in 2013 by the Icelandic studio Plain Vanilla, and shortly after launch it was among the fastest-growing apps ever — helped by the huge selection of topics and the social element of profiles and leaderboards by individual category. Still, the studio failed to find a long-term sustainable business model based only on ads and cosmetic purchases; the game passed to publisher Glu Mobile in 2016, and a few years later the online service was permanently shut down, so today QuizUp no longer works in its original form and can no longer be downloaded or played.

A simple, clean visual style emphasizing large topic photos and a clear interface made the app a very pleasant experience during its heyday even for casual players, who appreciated being able to compete only in topics they genuinely enjoyed instead of a generic, undifferentiated quiz.

Why play it: Historically, QuizUp is an interesting reminder of the early era of real-time mobile trivia, but no one can play it today since the service was shut down and the game disappeared from stores.