This is a complete devkit for Unity 3D game engine (http://unity3d.com/) for creating Flappy-Bird style games.You can use the FREE version of the Unity the Professional version is not needed! Unity version needed: 4.3.x, tested on 4.3.4. added new assets (background image), and the bird is animated now, tuned the game logic settings to be more like the original one. Added a new demo, that is exactly the same what you will see if you buy this package: https://github.com/icedev576/flappybird-devkit/blob/master/flappy_devkit_demo.apk
It is working with Android, IOS, Windows Phone, and all other Unity target platform. But I only attached an adMob advertizing client, which is for Android only, you can add more.
This is a complete working game, but I used NGUI for the menu (start/score buttons), so I can not include it in this project, but there is help to do it with your code.Written in C#, clean well commented (full) source code is part of the project. Support and Documentation: https://github.com/icedev576/flappybird-devkit