Crossing the River
This is an ancient puzzle. Your aim is to transport a gnu, a penguin, and a fish to the other river bank. However only one of these will fit in the boat along with you. If you leave the gnu alone with the penguin she'll eat the penguin. If you leave the penguin alone with the fish he'll eat it. Luckily the gnu won't eat fish. Select one of the animals by clicking it with left mouse button to move it onto the boat. Click the animal on the boat to move it to the bank. Click the hand icon to move the boat to the other bank.