Flappy Bird is a silly game in which you tap on the screen of your touch device to nagivate a (duck?) through a series of narrow paths delineated by tubes sprouting from the sky and ground. In the tradition of older 8 bit video games it's extremely unforgiving one mistake and you have to start over. It's apparently been a big hit. In regard to who the guy is, he is the developer of that silly game which he did for fun part time, it's blown up and he is tired of people harassing him. As to why people should care? I leave that as an exercise for the reader.