Nice - I'll throw up a simple version with a couple of corrections to start with and in the future look to do something a bit more complicated like that :)

You're right there, I think I'll make a second version where it's all in the counter actor. I'll also slow the thing down, at the moment you can sometimes barely see it when it changes so quickly!

This is - odd. I have to refresh the page rather than just clicking reset, otherwise they all change to orange in a flash! Is this likely to be me not coding very well at 1 in the morning, or a bug in Greenfoot somewhere along the line?