Bunno's Fabulous Soap-Making Challenge is intended to be both, a game that is played for fun and a game from which subject content can be learned. The game is modeled on and represents authentic, real-world chemical processes. Specifically, it promotes the learning of aspects central to the soap-making process. The game is a resource-managing game in which players plan, organize, and execute the production of soap. Players source the raw materials, acquire the technical equipment, create an efficient lab setup and produce and sell soap in an economically sustainable way. The game is centrally based on the idea of constructivist learning. Players encounter an inspiring and challenging situation and are active, in control, and make their own decisions and experiences. Their actions trigger immediate responses and are consequential. The main contribution of this article is a detailed description, a conceptual explanation, and a critical discussion of the game design. In addition, this article briefly describes the educational theory which informs the project, how the game design is actually realized in the implemented game and how it can be played, and the game's educational content and the projected learning outcomes.