Despite the game being wildly popular the developer of Flappy Bird decided to pull the game from the the Apple App Store. Fortunately there are three ways you can get the game back on your iPhone or iPod Touch:
If you have downloaded Flappy Bird in the past you can restore the game from your iCloud Backup:
- Open the App Store app
- Tap on “Updates”
- Tap on “Purchases”
- Scroll down through the list to Flappy Bird and tap on the cloud download button.
And Flappy Bird will install!
If you’ve never downloaded Flappy Bird in the past then find a friend who has and ask them to login to their iTunes account on your iPhone. Then they can simply download Flappy Bird from their iCloud backup as described above.
You can find details here: http://www.ilounge.com/index.php/articles/comments/using-apps-from-multiple-accounts-on-a-single-ios-device/
If the above two methods don’t work then your last resort is to jailbreak your device and download Flappy Bird from a third-party website. WARNING: Jailbreaking will void your warranty and could break your device. Only do it if you know how to do it. In additional downloading Flappy Bird from a third-party website is considered piracy by most governments.
I won’t link to any website that describe the detailed process for method three but you can find instruction by inserting into Google “How to jailbreak iPhone” and then “How to install Flappy Bird jailbreak”.