As an avid iOS gamer, I've heard about the Flappy Bird craze and controversy, though I never played the game myself. Flappy Bird was created by a Vietnamese developer in the Summer of 2013. It was a free, simple game with no in-app purchases. For whatever reason, it went viral in December. The fame (and infamy) was too much for the developer, who didn't expect or want the popularity. He was being harassed online and was even sent death threats. Eventually, he decided to pull the game to get everyone off his back though he's still making games.
If you ask me, pulling the game did nothing but create more interest in it. There's dozens of other games out there imitating it's style now, such as Ironpants and Flappy Bee. Heck, there's even conspiracy theories out there saying that Nintendo or even the Vietnamese mafia forced the developer to pull Flappy Bird. The Nintendo conspiracy theory was later discredited. I'm surprised such a small and simple free game was able to gather so much controversy.
I got my news about Flappy Bird from Touch Arcade, an iOS gaming news site. The forums there are a mess. There's people on there ridiculing Flappy Bird and it's developer and spouting junk like how "true gamers" would never play a simple game like that. Those people sicken me. I understand that people may not like Flappy Bird or are interested in it, but the developer is not a bad guy. He just made an incredibly simple game that happened to get unexpectedly popular.