Notch is an app that keeps track of scores for any kind of game. The app uses the strong and compact Trim for big type, such as scores, and San Francisco (the iOS system font) for small type. On the website and blog Adelle Sans is the text face.
Maybe Florian and I can keep track of how many Uses we each moderate each day on Fonts In Use. Fortunately he doesn’t have an iPhone so I am spared the embarrassment of seeing that particular personal deficit quantified.