Worldbuilding - the creation of imaginary worlds - is accomplished through a number of elements, such as visuals, narratives, environments, landscapes, and cultural elements such as languages and art. One of the most important aspects of constructing a fictional world in science fiction is the music. Whether diegetic (in-world) or atmospheric, music can help set the mood, illustrate the intentions of in-world characters, and considerably deepen a fictional world’s impact. In this talk I introduce the concept of sci-fi worldbuilding through music. I then perform a live musical improvisation that will be based on an imaginary game setting, character, or scenario given to me on the spot by the talk moderators/attendees. In this way I illustrate a composer’s workflow and thought process when creating the music that helps support the building of a fictional world.