Serious games have potential for facilitating change processes but require rigorous, interdisciplinary design to be effective. A novel, rapid online work-flow was developed for co-design of games for change with school teachers. Major design challenges included: short timescale; appropriately scaffolding a complex process; remote online interactions; and interdisciplinary commu-nication. The resulting workflow is highly visual, structured, and focused on swift knowledge exchange between pedagogy and game experts, drawing on relevant frameworks. Two workshops used the new method, producing eight co-designed serious games. Analysis suggests the workflow is effective for knowledge exchange for the rapid and rigorous co-design of serious games and has advantages for inclusivity and confidence in the co-design process.