Wurst-clien...: Download Wurst V6.21 Mc1.12 Offile:

Unzip the downloaded folder. Do not run the installer from inside the zip file.

You can now use Wurst features on Minecraft Realms for both the standard 1.12 version and the 1.12 OF build. Download Wurst v6.21 MC1.12 OFFile: Wurst-Clien...

Click the "Install" button. You should receive a success message. Unzip the downloaded folder

Locate the Wurst Installer.jar (or .cmd for Windows) and run it using Java. Download Wurst v6.21 MC1.12 OFFile: Wurst-Clien...