I don’t know exactly what you are trying to do, but I’m going to take a guess. You are trying to clear this level to start a new level. My recommendation is never to remove the viewport. Papervision3D and Flash are not great for cleaning up memory, so always use the same viewport. What will need to be done instead is cleaning up all the objects in the scene that are not needed (Environment objects) instead. So go through remove them and set them to null.

removeChild(viewport);

stage.addEventListener(MouseEvent.CLICK, setup, false, 0, true);

it works but it seems doesn’t clean up the previous game. Any idea?

BTW, it’s fun to play around such great stuff. Thanks!!