How to Decompile the Minecraft Game JAR (client.jar)
Decompile Minecraft itself, not a mod. Get the obfuscated client.jar, apply Mojang's official mappings, and read the game's source — plus what the licence allows.
What You Get Without Mappings
Step 1: Find the Game JAR
Step 2: Get the Official Mappings
Step 3: Remap the JAR
Step 4: Decompile the Remapped JAR
The Shortcut: Let a Toolchain Do It
What the Licence Allows
Summary