Hit mobile game Flappy Bird has disappeared just days after its meteoric rise, and rival developers have wasted no time launching copycats. Games like Ironpants and Flappy Bee take the same tap-to-fly formula made popular by Flappy Bird, building on that titles simple gameplay mechanic with unique visuals and power-ups. The infuriating yet strangely fun Flappy Bird was no innovator in its own right.