An app that began as an April Fools joke has become a worldwide phenomenon, achieving more than 15 million downloads in the space of a week, and an estimated $1.6 million daily in revenues.

The Pokemon Go app, has been downloaded more times in a week than the dating app Tinder has in its four years of existence, with Nintendo having to pause the game's global roll-out, in order to boost server capacity.

Game developers around the world watched in astonishment as the mobile version of the 1990s game became an instant hit following its launch last Thursday, adding nearly $10 billion to the company’s market value.

The app, developed by Niantic Labs, sees players walk around real-life neighbourhoods to hunt down virtual Pokemon characters on their smartphone screens and capture them.

The craze around the game is a huge step up from its humble beginnings as an April Fools joke launched by Google in 2014.

For one day, Pokemon appeared on Google Maps, letting browsers search for them at real-world landmarks.

“People seemed to really love that combination of Maps and Pokemon,” Niantic Labs chief executive John Hanke said.

The augmented reality game, which has more than 65 million users in the United States just seven days after launch, is surpassing Facebook, Snapchat and Instagram in time spent on the app.

Shops have begun attracting customers by advertising themselves as “Poke Stops,” a place where gamers can grab new Pokemon balls and increase their level of power within the app.

L’inizio Pizza Bar in Long Island City in New York said its sales jumped 75 per cent over the weekend by activating a “lure module” feature that attracts virtual Pokemon characters to the store, thereby tempting in nearby players.

The store’s manager spent $10 to have a dozen Pokemon characters placed in the location.

Mr Hanke sof Niantic said “sponsored locations” would provide an additional revenue stream, in addition to in-app purchases of power-ups and virtual items.

Additional reporting: Bloomberg, Reuters