In this paper, we discuss the development of young people's interactive storytelling skills within a game creation environment. We describe the Gamemaker workshop series, in which young people learn to use a commercial game creation environment to develop interactive, branching stories within a 3D virtual reality role-playing environment. Given this new medium for story expression, we sought to better understand the ways in which the young people choose to express their story ideas, in an attempt to provide further support and scaffolding for their developing narrative skills. In particular, we looked at the plot themes they chose to explore, the ways in which they included interactivity in the story, and their use of characters to tell their stories.