The game is no longer available to download for either Apple or Google users but its fans can still have fun if they have already downloaded the game to their devices.

Nguyen Ha Dong, a Hanoi-based game developer, announced the grounding of the addictive game in a Tweet on Saturday. He also apologised to Flappy Bird users.

"Twenty-two hours from now, I will take 'Flappy Bird' down,” Dong said, adding that it is not related to legal issues.

"I cannot take this anymore," he wrote.

Flappy Bird caused a sensation after rising from obscurity to become one of the most downloaded mobile games on both Apple and Google’s online stores.

Users have to steer a bird between green pipes. The Android version has been downloaded up to 50 million times and attracted more than half a million reviews.

Many people have been questioning Dong on Twitter about his decision to take down the game as a day earlier he had been talking about developing the game for Microsoft’s Windows phones.

Dong could not be reached for comment.

Unlike other successful game makers like Rovio Entertainment, which produced the hugely popular Angry Birds game and has hundreds of programmers, Dong made Flappy Bird in a few nights, he said on Twitter earlier.

The game, which he said was inspired by Nintendo’s Mario Bros, has been earning on average $50,000 a day from advertising, Dong said in a media interview.

Two friends of Dong said Nintendo had sent him a warning letter, but the Japanese game maker said it was not considering a lawsuit.

"It sounds very much like a rumour and if it is, we certainly can't comment on that," Nintendo's media representative told reporters on Friday.

The manager of a gaming company manager said Dong's decision to take down the game was wise.

"Dong is taking one step back to avoid legal risk because it's too difficult to deal with legal issues…..," said Duy Doan, a senior manager at VTC Online, one of Vietnam's leading game companies.

Dong had earlier said that he was not looking for investors and would not sell the game.

According to an expert, the investors would not be interested.

“Flappy Bird is not to the taste of many game investors because it's just hit-based, which will bring very uncertain cash flow and no recurring," said Nguyen Hieu Linh, investment manager at the Japanese CyberAgent Ventures Inc.