void Update()
    {
        switch (state)
        {
        case AppState.menu:
            if (Input.GetKeyUp(KeyCode.Escape))
            {
                if (!observerUI.Close() && !menuInfo.Close())
                {
                    Application.Quit();
                }
            }
            else if (Input.GetKeyUp(KeyCode.Menu))
            {
                menuInfo.Toggle();
            }
            break;

        case AppState.scenario:
            if (Input.GetKeyUp(KeyCode.Escape))
            {
                EnterMenu();
            }
            break;

        case AppState.observer:
            if (Input.GetKeyUp(KeyCode.Escape))
            {
                EnterMenu();
            }
            break;
        }
    }