Apps with an achievement system?

I’m looking for an app with some kind of achievement system. Preferably, this app would fall under the category of either gaming, productivity or social media. I want to be able to gain achievements within the app by using it. It doesn’t have to be anything special, I just really like the idea of pursuing achievements on an app for fun in my free time. You could branch out a bit and go to arts/graphic design or fitness and health if you want. I’d also appreciate if you could find more than one. Thanks!