I use Sky Force 2014 on two different Android devices A and B. After using Sky Force 2014 on device A, how can I retrieve the progress on device B? I can connect to Facebook and Google if needed. I'd also be interested in synchronizing with my 3rd device, which runs on iOS.
When you start the game for the first time on your second device, pass the initial demo play and the first real game play to enable the "High Scores" section's button. When its icon is enabled, press it, enter the high scores page and see the "Play Games" account icon at the bottom of it. Just press it and your account will be synchronized automatically. It takes a few restarts to fully synchronize all your progress (former purchases, extra planes etc) into the second device.