Mobile game Flappy Bird, which is developed by Vietnamese programmer Nguyen Ha Dong, has topped the App Store and Google Play Store charts after making its way to the top 10 lists of the two electronic stores for about a month.

With 50 million and over 10 million downloads from the Apple store and Google Play Store as of February 6, respectively, the app is raking in some $50,000 daily from in-app ads for its Vietnamese developer who lives in the capital city of Hanoi.

The 894 kb app has accumulated over 47,000 reviews from 591,300 ratings in the App Store — as many as apps like Evernote and Gmail, and 291,750 reviews in the Google Play Store.

The game is quite simple: a player has to tap the screen to propel a tiny bird upwards, and if the bird hits any green pipes that block its way when flying to the finish line, the game is over.

Dong told US technological newswire The Verge that Flappy Bird is so popular because it is different from other mobile games, and is a really good game to play against friends.

"People in the same classroom can play and compete easily because [Flappy Bird] is simple to learn, but you need skills to get a high score," he told the US newswire, adding that as the app is compatible with Apple's Game Center and Google's Google Play Games, it's easy to compare scores with friends and share the scores on Facebook and Twitter.

Dong has two other apps available via the two stores, Super Ball Juggling and Shuriken Block, but neither game combines challenge and entertainment as well as Flappy Bird, the US newswire reported.

Dong said that the games' mechanics are inspired by the Nintendo game Cheep Cheep from Super Mario Bros, which Dong played when he was a child.

"I want to make an ads-based game because it is very common in the Japanese market — mini games are free and have ads," Dong told The Verge. His studio, Gears, is working on their next project, a fresh take on the popular "Jetpack" genre of mobile games.