The how to design worlds process provides guidance for designing interactive world programs using big-bang. While some elements of the process are tailored to big, the process can also be adapted to the design of other interactive programs. The wish-list technique can be used in any multi-function program. World program design is divided into two phases, each of which has sub-parts: domain analysis (use a piece of paper!, sketch program scenarios b. c. d. Do a domain analysis by hand-drawing three or more pictures of what the world view will look like at different stages when it is running. Use this picture to identify constant information such as the height and width of screen, color of the background, the background image itself, the length of a rework"s fuse, the image for a moving cat and so on. Also identify changing information such as the position of a rework, the color of a light, the number in a countdown etc.