When the game starts, the first thing happening is that all the sheep on the computer players' islands get converted. It takes a few seconds for that mass conversion to take place (depending on your machine). During that time, the game seems frozen.
Then, the mini map looks like the one in the screenshot.
What happens next is really funny. You know how sheep converted by computer players move "on their own"? Well, now the computer players' towncenters get literally crowded by sheep. So much so that their villagers can't move anymore. Basically, the AIs get immobilized by their own efficiency. The challenge would of course be to prevent this from happening.