Players advance their frog by taking frogs from the bag and placing them on the board. But some frogs don't like others - so frogs also have to be at the right color. By placing frog of the wrong color You find Yourself right where You started. But You can always stop risking and say that You'll stay right where You got with the last frog. At Essen '08 there also was this poster: "These frogs are not edible!"