Thank you both for your answers! The point is when I uninstall a game from android, the saves are automatically deleted. So, when I reinstall the game, I have to play again from the beginning. Such a headache! I didn't realize, that I need to make a backup.
When you uninstall an app Android clear it's data, that is, in this case, deleting
Android/data/com.saddog.the.tyrant
If you want to have conserve your previous saves you have to go to
Android/data/com.saddog.the.tyrant/files
Where you will find a folder "Saves" and a .txt file, log.txt.
You have to move (aka, copy and paste) your "Saves" folder out of com.saddog.the.tyrant after doing so you can uninstall the app.
After this you only have to download the new one and execute it once (because the application only creates the folder com.saddog.the.tyrant after being executed once), after that you just have to move (aka copy and paste) your "Saves" folder to
Android/data/com.saddog.the.tyrant/files
If it pops a window asking you something say yes (because the game may or not create a saves folder even without you starting any play).
And that's all, now you'll be able to open the app and find your previous saves there.
Finally, you can also use this to move saves from the PC to Android and vice versa.
