Based on the search term "save editor rxdata," it is highly likely you are looking for a tool to modify RPG Maker games (specifically XP, VX, or VX Ace), as .rxdata is the default file extension for their save files.
Download and install the chosen save editor. Make sure to select a reputable source to avoid malware. save editor rxdata
require 'marshal' # not necessary; Marshal is built-in
Game Modding: Extracting Scripts.rxdata to individual Ruby files allows developers to use modern IDEs like VSCode for coding instead of the basic built-in editor. Based on the search term "save editor rxdata,"