   space invaders effects
  how do i create  the green blocks ?It is not an image and it is simply drawn and when you shoot it , it crumbles .How do i create this effect of shooting down the green block?http://www.spaceinvaders.de/   
  It's simply just a square block that has an associated "health" with it.  If the block has full "health," you draw it as a full green block.  When you shoot it, it looses "health" and, depending on how much "health" it has, you just draw different versions of the block.You could easily create a set of images, the first one being the full block with full health, the next image being the block missing a few pieces after being shot once, the image after that missing a few more pieces after being shot again, etc.  Then, for each time you shoot the block, you just move down the list of images that show a slowly degrading, crumbling block.  Once the block looses all its health and is destroyed, you just remove it from the game.   