Just press space to move between screens.
This is not a full demo, I'm using one sprite for the whole of the snake's body but the idea is that each grid position would contain one section of the body. The grid can also be used to record where walls are etc making it easy to detect whether the snake's head (the only bit we need to worry about!) can move into the cell it's heading into. this is a good project to use 'stamp' in as you can just stamp the different bits of the snake's body and overstamp with the background to clear a cell.
