Bummer! There actually IS an auto-save and auto-backup feature of the Geany editor but it is not enabled by default. Here's a quick tutorial:
1.) Open AppGameKit IDE.
2.) Tools > Plugin Manager.
3.) CHECK "Save Actions"
4.) Click "Preferences"
5.) Set the options for "Auto Save" such as save every 'x' seconds or whenever focus is lost.
6.) Optionally set "Instant Save" which will save in real-time as you type but this is probably overkill.
7.) Enable "Backup Copy" and specify backup location, preferably on a different drive.
8.) Set the "Directory levels to include in the backup destination" to '1' or '2' so that the scripts per project will be contained within their own folder in the backup directory.
8.) Click "Apply" and "OK".
Now whenever you save the file (or every 'x' seconds) a backup file of the current script will be saved as well in the default format of: "script.agc.YYYY-MM-DD-HH-MM-SS".