
jars: Get a copy of the 1.2.5 client Minecraft. Alternatively, download the latest release (LWJGL 2.9.3) from here.
LWJGL: If you want to use an authentically janky old version of LWJGL, download LWJGL 2.4.2, which can be found here (download the file named "lwjgl-2.4.2.zip"). Copy this file to where you're storing all of these downloaded files. You can find the fernflower.jar file at /mcp70a/runtime/bin/fernflower.jar. Download mcp70a from the same Minecraft wiki page, and unzip the files. Luckily, this version of Fernflower can be found in mcp70a. This version of Fernflower is important, as using newer versions of Fernflower will break Forge's patches, which were intended to fix some of Fernflowers decompilation bugs at the time. Fernflower: You'll also need to obtain a specific version of Fernflower, as the automatic download link mcp62 used is now non-functional. The Minecraft wiki has a list of MCP versions with download links here. MCP: Download the Mod Coder Pack for 1.2.5 (mcp62). These can be found on the official Forge website. Forge: Download the Forge 1.2.5 source distribution you'd like to use (it's recommended to use the latest released version). Make sure to always have a backup copy of all of these downloaded files! I'd recommend putting them into a seperate folder from your MCP / Forge project directory. The links have changed and Minecraft 1.2.5 isn't able to download them anymore. TODO: Add a section on installing the resources (sounds) folder to the MCP environment. #MINECRAFT JAR 1 5 2 HOW TO#
How to set up a Forge 1.2.5 workspace in 2020 & above.