Patent US 6,366,288

In an image display device, a ROM contains a plurality of image data indicative of the actions of an animal character. A RAM includes a plurality of action level registers each stores for each of which image data the state of inputs given to select and display the image data. The user gives a command corresponding to a respective image of an animal character to select and display the action of the animal character optionally. When a random number corresponding to the command is generated, image data which does not correspond to the input command can be displayed. If the generated random number has a particular value, the value of an action level register for the image data corresponding to the command is updated. Such operation is iterated and thus the value of the action level register is updated. When the user instructs the device to display the image data for which the updated value of the action level register has reached the predetermined value, the corresponding image data is displayed, so that the user can interestingly feel as if the user actually kept a pet.