First of all, go into the trophy room. There would be a star on the left hand corner. If you don't see it, exit trophy room and try again. And to unlock this secret mode, click on at least five different trophies. ( You need to earn at least five trophies for it to work. It doesn't matter any kind. ) Everytime you click on one, another star appears. Click until you see five stars on the top. Then exit trophy room and the mode will appear on the Menu screen.