It is designed for Advanced Slime World Manager (Advanced Slime Paper). Since by default, all the worlds which is from slime format, will not save game rules. Therefore, you must manually set all the game rules again for all worlds when you restart the server.

With this plugin, you no longer need to set all the game rules manually when the server starts. This plugin will automatically handle it

*For those worlds created using the default method, including Multiverse Core, you don't need to use this plugin. Those game rules are saved in the world data.
*Also, some of the mini-game plugins like Skywar, Bedwar, and Skyblock also handled the game rules by itself

Command:
/set-gamerule <world> <gamerule> <value>
Permission:
restoregamerule.setgamerule

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I will format the description better when I have time