Woolah - Knockout Photo challenges with your friends.
Scenehunt - Search, share and explore Film and TV shooting locations
QuizUp - QuizUp gives you the opportunity to test your trivia skills against friends and strangers throughout the world.
yapQ - Turn your smartphone into an audio tour guide
2016 Photo Challenge - Take a photo every day for 366 days
Tramble - The codebreaking walking challenge. UK only