Using the application without Java installed

[nordlicht]

• Get a JRE folder (you can do this by installing Java, copy out the "jre1.x" folder from program files to somewhere, then uninstall).
  

You don't have to install Java first, just use this: https://portableapps.com/apps/utilities/java_portable

You could also go one step further and start RC with the JavaPortable_Launcher, then it won't even write its settings to the registry.