FlappyBird.com is described as 'Play the game Flappy Bird now online at the official FlappyBird.com'. There are more than 25 games similar to FlappyBird.com for a variety of platforms, including Android, iPhone, Android Tablet, iPad and Online / Web-based. The best alternative is Flappux, which is both free and Open Source. Other FlappyBird.com like games are A7X Flap (Free), Flying 2048 (Free), Flappy Bird Online (Free) and Floculus Bird (Free).
99 Problems is a small game consisting of 99 seamless levels of minimalistic, challenging, jumping action. Navigate a seamless stream of obstacles by evading and wall-jumping your way to the next checkpoint.
In Tricky Sky you must fly as far as you can while avoiding the bats. Catch the right flow, and maybe you'll get through the tricky sky. Be sure to collect some gems on the way, to unlock new birds and planes! Or just pick up a star, and become invincible.