As the key visual display- and processing- element of information super highway nodes, computer graphics is advancing into dynamic and higher dimensional visual worlds. So is visual algorithms to program visual worlds as the contents of information super highways. This research presents a drastic approach in designing visual algorithms to construct visual worlds. The address is on the most critical phase of conceptual design that has been conducted ad hoc in designers' mind. Conceptual visual algorithms make mental design processes and design results explicitly represented in a computer executable form after interactive machine translation. Hence, they are explicitly validatable against the design requirements. Taking a popular case of human performance design including dramas, music performance and sporting, recreational skiing algorithm design in particular as an example of visual world design, we show a requirement-driven approach to conceptual visual human algorithm design produces a truly effective skiing method to meet wide varieties of recreational requirements.