Flappy Bird hits No. 1 on the app stores. But why?

Flappy Bird has topped the charts of free mobile apps in the iOS and Google Play app stores.

It is a silly free game, and that fact that it has climbed so high in the past week is a sign that we’re all just a little nuts.

But it’s nice to see an unknown game shoot ahead of Snapchat, the company that turned down a $3 billion offer from Facebook. It is also ahead of Beats Music, Facebook Messenger, Clash of Clans, and YouTube on Apple list of the top free apps. And yes, it’s a lot more popular than any Angry Birds game right now.

You play a pixelated “Flappy Bird” in the game. You tap the screen and try to fly past green posts that look like the pipes in Nintendo’s Super Mario Bros. (In fact, we may not want to mention that to Nintendo’s lawyers.) If you hit a pipe, the game is over. It gets more challenging as you go. And that’s it.

My kids say that everyone is playing it. And it has caught their attention because it’s so hard. Evidently, the game’s appeal lies in how frustrating it is. We only spotted it because John Gargiulo of BlueStacks, which makes software that runs Android apps on other platforms, pointed it out to us.

“In my years in mobile, I have never seen anything like this,” he said.

The game was created by Vietnamese developer Dong Nguyen of dotGears Studios. It has more than 240,000 four-star reviews on iOS. On Twitter, he describes himself as a “passionate indie game maker,” and says he lives in Hanoi. According to AppAnnie, the game was uploaded on May 24, 2013. It’s not clear why it just became so popular in the last week. Nguyen has created two other games: Shuriken Block and Super Ball Juggling.

Nguyen has been enjoying himself chatting with people who say the game is too hard. He said to one Twitter member, “Girl, actually it was made to make you laugh.” To another, he said, “You should take a break.”

He told one journalist on Twitter that he wasn’t comfortable doing an interview. We put in our request too, and in the meantime, he did this interview. While the game may not have a point, it has proven once again that anything can happen in the wild world of mobile gaming.

Zynga just paid $527 million for mobile game maker NaturalMotion, the creator of Clumsy Ninja and CSR Racing. I hear dotGears Studios may go for $600 million.

Carter Thomas of Bluecloud Solutions thinks it’s too good to be true and that dotGears is using bots to scam the rankings. If so, we’ll see those rankings change dramatically once Apple and Google weigh in.

Meanwhile,Sarah Young of NativeX, has her own take on why the game is so viral.