EOS-503 is a free, publicly available browser-based roleplaying game designed to help teacher education programs compare their students’ application of instructional practices, technology integration skills, and visionary leadership with traditional evaluation measures like exams and portfolios. Developed by and for teachers, all interactions between the player and non-player characters (NPCs) are bona fide representations of the thinking and action employed by real-world educators in real-world teaching and learning environments. This approach is particularly effective for humanities content—philosophy, history, education—where designers can help the player “think like a philosopher,” “think like a historian,” or “think like a teacher.” Players are tasked with persuading the game’s NPCs to change their points of view, first by identifying specific cognitive theories at the heart of an NPC’s worldview, then by deciding which dialogue options have the highest probability of successfully influencing a given NPC’s thinking. Unlike multiple-choice tests or essays, EOS-503 leverages responsive roleplaying elements and branching plotlines to bring learning theory to life—every conversation incorporates multiple philosophies to be explored, and every player choice branches into dozens of potential story outcomes.