The aim seems as simple as the graphics are basic: to fly a yellow bird through a series of pipes. If the bird hits the ground or touches a pipe, it's game over.

Yet Flappy Bird has been downloaded an incredible 50 million times, and has been top of the Apple App and Google Play stores for the past month, netting its Vietnamese inventor Dong Nguyen £30,000 in ad revenues every month.

Its combination of simplicity and difficulty is seen as key to its playability.

"Your first thought is 'Oh, this is really easy!'" Dr Andrew Przybylski of the Oxford Internet Institute told the Times.

"But very quickly you realise that, actually, no it's not."

While studios spend months and hire whole teams of designers to hook gamers on the latest must play app, Nguyen said he designed the game over the course of a few days after he got home from 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 in an interview with the Verge.

"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."

He said that despite its success, he intends to leave the game untouched for the time being.

"Flappy Bird has reached a state where anything added to the game will ruin it somehow, so I'd like to leave it as is," he says. "I will think about a sequel but I'm not sure about the timeline."

The game is free to download, and is not the only hit Nguyen has on his hands, with his Super Ball Juggling and Shuriken Block both in the Apple top ten.

Fans though say neither matches the frustrating yet compelling Flappy Bird.

"There is a meta-aspect here, of being able to laugh at Flapping Birds while at the same time enjoying it. It allows you to reflect on the larger silliness of playing," reflected Przybylski.