NewGame options allow us to directly launch a new playthrough into our custom world or using our own main quest. The snippet below demonstrates how to add the option into the main menu, and then how to listen when the option is used to dynamically launch a new playthrough into the world we want

@wrapMethod(IngameMenuStructureCreator)
function CreateNewGameListArray(): CScriptedFlashArray {
  var l_ChildMenuFlashArray: CScriptedFlashArray;
  var l_DataFlashObject: CScriptedFlashObject;
  var output: CScriptedFlashArray;

  output = wrappedMethod();

  // then inject our own NewGame option
  l_DataFlashObject = CreateMenuItem(
    "NewGame",
    "new_game_wmh1",
    NameToFlashUInt('WildMonsterHunt'),
    // IMPORTANT: pick a random number above 27 that is not 100.
    //
    // This number is then passed as the `actionType` in the wrapper below,
    // you must then check against that number to detect when your NewGame is
    // used.
    76,
    false,
    "newgame_difficulty"
  );

  l_ChildMenuFlashArray = CreateDifficultyListArray(IGMC_EP1_Save);
  l_DataFlashObject.SetMemberFlashArray("subElements", l_ChildMenuFlashArray);
  l_DataFlashObject.SetMemberFlashString(
    "description",
    GetLocStringByKeyExt("panel_mainmenu_start_wmh_description")
  );
  
  output.PushBackFlashObject(l_DataFlashObject);

  return output;
}

@wrapMethod(CR4IngameMenu)
function OnItemActivated(actionType: int, menuTag: int): void {
  // see the IMPORTANT comment above explaining this random number,
  // if the number matches then we may launch a new game using our .redgame file
  if (actionType == 76) {
    fetchNewGameConfigFromTag(menuTag);

    theGame.SetDifficultyLevel(currentNewGameConfig.difficulty);
    theGame.RequestNewGame("levels\wmh_lv1\wmh_lv1.redgame");
    theGame.HideHardwareCursor();
    theGame.GetGuiManager().RequestMouseCursor(false);
    OnPlaySoundEvent("gui_global_game_start");
    GetRootMenu().CloseMenu();
  }
  // otherwise let the vanilla scripts, or any other wrapper handle the other
  // values 
  else {
    wrappedMethod(actionType, menuTag);
  }
}

For the snippet's code the following lines will have to be localized:

• new_game_wmh1
• panel_mainmenu_start_wmh_description

After you've edited the snippet to link to your world ensure that you localize your strings as well. The two keys above should help you figure out which variables are expected to be localized.