This plugin is focused on automatically synchronizing save files, whenever you save the game. For example, if you turn ON a switch and then save the game, the switch will be turned ON for all other save files as well.
You can even check this switch in the title screen, which allows you to have in-game decisions affect things outside of the game.
Currently, any switches and variables can be synchronized.
What kind of things can you do with this?
Release Page: http://himeworks.com/2015/12/sync-save-data/