Gamers' expectations have never been higher. For next-generation character-based action games, this means more moves, increasingly complex locomotion systems, cooler enemies and scenarios epic in scope. In response to this avalanche of content, THE INCREDIBLE HULK: ULTIMATE DESTRUCTION team developed a GUI-based decision tree and state machine editor called the Gym. It allows rapid creation and iteration of nearly all aspects of gameplay content; including character mechanics, AI behavior and mission scripting. The result is a run-time efficient, designer-friendly technique for producing "action on the Richter scale." This session will focus on code techniques used for implementation of the tool, as well as the workflow issues arising from integration of the Gym into the production pipeline.