App Name: Trivia.Town [Android, iOS Game]

Cost: Free

Developer: Trivia.Town

App Market: Download Page

Description:

Features:

– 20.000 questions in 10 categories.
– New questions in every game. All of them with an explanatory picture.
– No popup-ads
– Challenge your friends (or foes), real time or whenever they accept your challenge
– Ranking is taken seriously.
– Add new questions wiki-style and see how well they do.