Extra Options

gamedir

The directory where worlds, mods and other files are stored. If it's not an absolute path, it's relative to the working directory where you run minecraft.
Can be overwritten with the "MINECRAFT_GAMEDIR" environment variable.

programs.minecraft = {
  enable = true;
  instances= {
    "example-instance" = {
      minecraft.version = "1.21";
      gamedir = "./1.21-gamedir"
    };
  };
};

extraGameDirFiles

A list of files to be copied to the game directory on game startup

programs.minecraft = {
  enable = true;
  instances = {
    "example-instance" = {
      minecraft.version = "1.21";
      extraGamedirFiles = [
        {
          path = "./options.txt";
          source = "${config.home.homeDirectory}/.minecraft/options.txt";
        }
      ];
    };
  };
};

cleanFiles

Files and directories relative to the game directory to delete on every startup.

programs.minecraft = {
  enable = true;
  instances = {
    "example-instance" = {
      minecraft.version = "1.21";
      cleanFiles = [ "logs" ];
    };
  };
};