Today I wanted to share a brief tutorial of how to successfully play a modded Minecraft in the new launcher. As many of you know, Mojang has been working on a new and improved launcher that allows for automatic updating, quick switching to and from multiple versions, and future modding API support. So far the one downfall of this new launcher is that it will automatically download new files if you modify your client in any way. However after some experimenting, I found a way around this.
First let’s take a look at the new .Minecraft folder structure:
Next go into the “versions” folder. Here we have all the different Minecraft versions that you have downloaded from the launcher so far.
Step 1: Make a copy of the version you want to mod or save. I renamed it “CUSTOM” for this tutorial.
Step 2: Next, rename both of the files inside to the same name that you named your folder. In this case it will be “CUSTOM”.
Step 3: Next open up your CUSTOM.json file in a text editor and edit the “ID” line to match the name of your folder.
Step 4: Lastly, open up the launcher and you will now see a tab titled “Profile Editor”. Click on this tab and create a new profile using the version you just created as shown below.
You can select this new profile any time you want to play it from the drop down menu on the right.
Other Methods and Notes:
Magic Launcher has been around since the early days of Minecraft. Since its creation, countless Minecraft players have used Magic Launcher as their go-to program to install and play mods. However with the introduction of the new launcher, these types of programs are gaining even more popularity due to their ease of use. Below are links to the Minecraft Forum page, as well as a simple video by AntVenom outlining the basic features of Magic Launcher
Credits: Wilderness Specialist