I tried to play Flappy Bird, but it was hard. I tried multiple times, only got best score of 7.

Flappy Bird

Flappy Bird looks nothing innovative as compared to other ones like JetPack. But why is it so hard?

Not until I wrote my own flappy bird, which I call racket-flappy, did I realized what was behind flappy bird. I was so surprised that in my own version of flappy bird, I could get 10+ passes.

Flappy Playing

Then I looked at the physics side. In my own version, the bird has a vertical speed v, a vertical position y and gravity g. v is influenced by g and y is affected by v, a common sense in high-school physics. Upon clicking, the bird’s vertical speed v is boosted by a fixed number. In other words, the click gives the bird an impulse. It’s a simplified version of the formula m*v = F*t, where m is the mass of bird, F is the force applied to bird and t is the time frame. Such model conforms to physics and should give no surprise to players.

But then it goes differently in the original version of flappy bird. Upon clicking, the bird is not boosted by an impulse. Instead, its vertical speed changed to zero and vertical position is increased by fixed amount! WTF… That surprises me a lot and you cannot smoothly control the bird anymore. By clicking, the bird’s vertical position changes dramatically and that causes most attempts to fail! Ah… What an anti-humanity game, Flappy Bird!