public Alien(int x, int y, String level, int difficulty) 
    {
        craft  = "Assets/Images/alien.png";
        craft2 = "Assets/Images/alien2.png";
        craft3 = "Assets/Images/alien3.png";
        craft4 = "Assets/Images/alien4.png";
        mode   = difficulty;
        
        if (this.mode == 2) 
        {
            fluc = 40;
        }
        if (this.mode == 3) 
        {
            fluc = 50;
        }
        this.level = level;
        ImageIcon ii = null;
        if (level.equals("1")) 
        {
            ii = new ImageIcon(this.getClass().getResource(this.craft));
            hp = 1;
        }
        if (level.equals("2")) 
        {
            ii = new ImageIcon(this.getClass().getResource(this.craft2));
            hp = 1;
        }
        if (level.equals("3")) 
        {
            ii = new ImageIcon(this.getClass().getResource(this.craft3));
            hp = 1;
        }
        if (level.equals("4")) 
        {
            ii = new ImageIcon(this.getClass().getResource(this.craft4));
            hp = 49;
        }
        image   = ii.getImage();
        width   = this.image.getWidth(null);
        height  = this.image.getHeight(null);
        visible = true;
        this.x  = x;
        this.y  = (double)y;
    }