LegacyChecker

A lightweight, fail-safe utility mod that ensures players have all mandatory mods installed before entering the game.

It elegantly solves license restrictions (like All Rights Reserved / ARR) that prevent modpack authors from bundling specific mods directly into modpack files.

Inspired by the concept of FTBChecker. This mod is exclusively for 1.12.2 and will not be ported to newer versions — please use modern alternatives for newer game versions.

REQUIRES CLEANROOM

📦 Configuration (legacychecker-common.yaml)

The mod automatically generates a YAML configuration. You can specify as many required mods as your pack needs.

    # List of required mods that must be installed for the game to run.
    # If any mod is missing, an error screen will block startup or show a warning.
    #
    # Structure per mod:
    #   - modId:   "The exact internal ID of the mod"
    #   - modName: "The friendly name displayed to the player"
    #   - url:     "Direct download link (CurseForge, Modrinth, etc.)"
    requiredMods:
      - modId: "jei"
        modName: "Just Enough Items (JEI)"
        url: "[https://www.curseforge.com/minecraft/mc-mods/jei](https://www.curseforge.com/minecraft/mc-mods/jei)"
      - modId: "gregtech"
        modName: "GregTech CE Unofficial"
        url: "[https://www.curseforge.com/minecraft/mc-mods/gregtech-ce-unofficial](https://www.curseforge.com/minecraft/mc-mods/gregtech-ce-unofficial)"

    # If true, the "Continue" button appears, allowing players to skip the warning.
    # If false, players must install the mods or exit the game.
    canPlayerLoadGame: false