Serious games have received attention among researchers and practitioners as a potential means for promoting professional development. While interest in serious games has been on the rise, business process models have, to date, only rarely been studied as building block of a serious game. We present findings of a field study into the design and application of an innovative serious game based on a business process model. Applied in an in-house training involving 500 employees at a medium-sized German manufacturer, the serious game aims to familiarize the players with the intricacies of the manufacturer’s complex tendering process—by challenging them to properly interpret and complement a BPMN (Business Process Model & Notation) model of the process. Following a hermeneutic research tradition, we seize the unique opportunity to study the design of the game and its application in training sessions in the field. In the paper, we report insights from studying the game design, from observations in training sessions and from interviews with participating employees, trainers and game designers.