put this in the world class: public void act() { for(int i = 0; i < 100; i++) { stars[i].move(); } } and remove the move(); line in the star class in the act method

addObject(stars[i], Greenfoot.getRandomNumber(getWidth()), getHeight()/2); this command is three times in the world class. you have to change the getHeight()/2 to Greenfoot.getRandomNumber(getHeight())

I just found one method to do this, but it slows the game a bit down. add this to the UpdateImage method before the return List explodeEm = getWorld().getObjects(Flame.class); Iterator i = explodeEm.iterator(); while(i.hasNext()) { Flame a = (Flame) i.next(); G2D_Graphic.drawImage(BI_GI_Light,null,a.getX()-GI_Light.getWidth()/2,a.getY()-GI_Light.getHeight()/2); }