@seal308, I sure it is just a matter of changing the image of the one actor. @sushi, there is a glitch, in that sometimes when a new frog appears under the snake (possibly just at the head) that the snake will not be able to eat it. Happened to me at 600, but I am sure it was just random chance.

@Duta, I cannot be sure. It was too long ago. This was like my 3rd project in Greenfoot. I am not sure if I was using static variables at that point. However, I noticed I had said that it compiled different each time; which indicates that it was probably something else.

There is another, older, scenario (2010/12/8) called 'Blocks' that has the same concept. It is at: http://www.greenfoot.org/scenarios/2253

A lot of folks have been asking about how to detect collisions, or how not to pass through objects, so I created this example which also has an example of how one can sub-class my 'Bar' class to give it some functionality.