How do I backup / save my game?

Probably by tapping the settings icon in the top left of the game screen. There you can connect to Facebook, Instagram and Google.

I would assume that connecting to one of these will allow you to restore your game if you start to play it on a different device by logging in again with the same social network account. But I've not tried this!

For more questions for Lumber Empire: Idle Tycoon check out the answers page where you can search or ask your own question.