A simple but hugely addictive video game is taking the world by storm. Bubble Ball is a physics-based puzzle game that has been downloaded as an app by more than two million iPhone users.
It became the top free application on the Apple store. But it hasn't been designed by a team of highly paid experts, it is the work of a 14-year-old boy, Robert Nav.
His game even outsold the adventure game Angry Birds. Since its release on December 29, Bubble Ball's success has become astounding. Adding to Robert's glory is the David versus Goliath nature of his victory.
While he designed Bubble Ball in his bedroom in Spanish Fork, Utah, Angry Birds was developed by 17 professionals in Finland.
The rules of Bubble Ball are simple - players must move a small blue ball from one side of the screen to the other by steering it around various obstacles.
Robert was encouraged to try his hand at programming by a friend who noticed how much he liked his iPod touch.
What were you doing when you were fourteen?