Flappy Bird was created by Vietnamese developer Dong Nguyen and quietly released in May 2013. For months, nobody cared. Then in January 2014, it suddenly went viral and became the most downloaded free app on both iOS and Android.

The game was absurdly simple — tap to flap, dodge green pipes, don't die. But the brutal difficulty made it dangerously addictive. At its peak, Flappy Bird was generating an estimated $50,000 per day in ad revenue for its solo creator.

Then on February 8, 2014, Dong Nguyen tweeted that he was taking the game down. Not because of a lawsuit, not because of a business deal — because he felt guilty. He said the game had become too addictive and was ruining people's lives.

Within 24 hours, Flappy Bird was gone from app stores. Phones with the game pre-installed started selling on eBay for thousands of dollars. Hundreds of clones flooded the app stores overnight. The internet had never seen anything like it.