PAD = Puzzles & Dragons, and it was a mobile game I really got into back in college and played for many years. In it, you pair with other players with certain characters to find dungeons, but the problem is that there wasn't a friend finder feature in-app. This app created a crowd-sourced solution to that problem.
3,500+ installs on Google Play with a ~3.9 rating after 50+ reviews 3 years ago