14-year-old's kid video game downloaded two million times

Promotional screenshot of the Bubble Ball iPhone app game.

A simple video game designed by a 14-year-old school kid is taking the world by storm.

Bubble Ball is a physics-based puzzle game that has been downloaded 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 Robert Nav, a teenaged schoolboy.

Nav's game even outsold the adventure game Angry Birds. Since its release on December 29, Bubble Ball's success has become astounding, the Daily Mail reports.

Adding to Robert Nav'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. Robert released Bubble Ball through his own company, Nav Games.