TotallyNotModded

Hint: Do not play existing worlds with the mod in place, if you are not prepared to play on the world with the mod forever (a long time!). It is therefore recommended to create mod-exclusive worlds.

Installation

Go to https://files.minecraftforge.net/net/minecraftforge/forge/index_1.19.4.html and download the installer for the 45.0.64 revision of forge.
After installing minecraft forge with the installer, start your minecraft launcher and create a new installation. Select the forge revision you just installed from the list.
Start the forge version WITHOUT the mod to make sure everything works fine. If so, close minecraft.
Download the version of the mod you want to play with and put it in your %appdata%/.minecraft/mods directory. You can find precompiled jars in the releases.
Start the forge version again, this time, if you go to "Mods" in the main menu you should see that the "TotallyNotModded" mod has been added to forge.

Source installation information for modders

This code follows the Minecraft Forge installation methodology. It will apply some small patches to the vanilla MCP source code, giving you and it access to some of the data and functions you need to build a successful mod.

Note also that the patches are built against "un-renamed" MCP source code (aka SRG Names) - this means that you will not be able to read them directly against normal code.

Setup Process:

Step 1: Open your command-line and browse to the folder where you extracted the zip file.

Step 2: You're left with a choice. If you prefer to use Eclipse:

Run the following command: gradlew genEclipseRuns (./gradlew genEclipseRuns if you are on Mac/Linux)
Open Eclipse, Import > Existing Gradle Project > Select Folder or run gradlew eclipse to generate the project.

If you prefer to use IntelliJ:

Open IDEA, and import project.
Select your build.gradle file and have it import.
Run the following command: gradlew genIntellijRuns (./gradlew genIntellijRuns if you are on Mac/Linux)
Refresh the Gradle Project in IDEA if required.

If at any point you are missing libraries in your IDE, or you've run into problems you can run gradlew --refresh-dependencies to refresh the local cache. gradlew clean to reset everything {this does not affect your code} and then start the process again.

Mapping Names:

By default, the MDK is configured to use the official mapping names from Mojang for methods and fields in the Minecraft codebase. These names are covered by a specific license. All modders should be aware of this license, if you do not agree with it you can change your mapping names to other crowdsourced names in your build.gradle. For the latest license text, refer to the mapping file itself, or the reference copy here: https://github.com/MinecraftForge/MCPConfig/blob/master/Mojang.md

Additional Resources: