The quick-fire round is always the best bit in game shows: Gimmicks are thrown aside and contestants are required to answer promptly and precisely. QuizUp distils the format into an app, as you engage in online duels with other trivia fiends. You can play against strangers or your own Facebook friends and choose from more than 250 topics and sub-categories, from general knowledge to more specialist subjects. So, for example, the music questions can be wide-ranging or divided by decade, genre, music theory and even specific acts. The app chooses an opponent, one who's roughly as skilled as you, and a one-minute quiz ensues. If you find a worthy adversary you can challenge them to rematches. The users tend to be mostly Americans, and the questions sometimes skewed Stateside. But this should change over time as the database and user-base grows, and players can submit their own questions. This free app tells you to involve your social media friends, but not too aggressively.