Custom Minecraft Launcher

A fork-ready Minecraft launcher designed to target a single version of the game. Ideal for server administrators and modpack creators who need a controlled, reproducible launch environment.

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Overview

This project provides a customizable Minecraft launcher built with Kotlin Multiplatform and Compose. Before building and distributing, you must override the configuration files and assets described below to tailor the launcher to your use case.

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Configuration

All configuration files are located in:

src/jcmMain/composeResources/files/config

GameConfig

Controls Minecraft behavior on first launch.

{
  "version": "1.21.11",
  "loader": "fabric",
  "loader_version": "0.19.2",
  "settings": {
    "renderDistance": 11,
    "fov": 0.5,
    "gamma": 1.0
  },
  "servers": [
    "mc.hypixel.net"
  ]
}

Field	Description
version	Target Minecraft version
loader	Mod loader — supported values: vanilla, fabric, forge, neoforge, quilt
loader_version	Version of the selected mod loader
settings	Initial values written to options.txt on first launch
servers	Server addresses pre-populated in the server list on first launch

LauncherConfig

Controls the launcher window appearance.

{
  "name": "CustomLauncher"
}

Field	Description
name	Title displayed in the launcher window

ResourcesConfig

Points the launcher to the remote modpack manifest. The file at the provided URL is downloaded at launch to resolve all mods, configurations, resource packs, and shader packs.

{
  "resourcesLink": "https://some.link.com/to.json"
}

To generate the resources manifest JSON, use the bundled script GenerateRessourcesJson.main.kts. Provide a .txt file listing your download links along with the JSON from a Modrinth export (.mrpack), and the script will produce the required manifest automatically.

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Asset Overrides

You can replace the following images in src/jcmMain/composeResources/drawable:

File	Purpose
icon.png	Application icon
logo.png	Logo displayed in the launcher UI
banner.png	Banner image

The application version can also be updated in:

src/jcmMain/composeResources/files/version

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Building

Run locally

./gradlew :composeApp:run

Package for distribution

Platform	Command
Windows	./gradlew :composeApp:packageMsi
Linux	./gradlew :composeApp:packageDeb
macOS	./gradlew :composeApp:packageDmg

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License

This project is distributed under the GNU General Public License v3.0.

You may not distribute closed-source versions of this software. Any derivative work must credit the original author. For full license terms, refer to the GPL v3.0 license.