Hit mobile game Flappy Bird collects on average$50,000 per day from in-app advertisements, the game’s creator Dong Nguyen told The Verge.

Flappy Bird became famous for its minimalistic yet incredibly difficult controls and has been downloaded 50 million times since launch. Players must keep the bird suspended as you navigate through a maze of pipes by tapping on the screen.

Nguyen told The Verge he built Flappy Birds over a few evenings after work. “The reason Flappy Bird is so popular is that it happens to be something different from mobile games today, and is a really good game to compete against each other,” Nguyen said. “People in the same classroom can play and compete easily because [Flappy Bird] is simple to learn, but you need skill to get a high score.”