This paper presents a theoretical framework that categorises the design paradigms commonly observed in ethically relevant games. This theoretical framework was developed based on game design factors responsible for the player’s decision-making process and their role in signifying morality in the gameworld. The model’s development was followed by an evaluation process constituting in-depth semi-structured interviews conducted with ten professional game designers with industry experience. Secondly, this paper proposes an oscillatory, system-based approach to ethical gameplay in serious games. In this approach, elements from both scripted and systems-based design methods are used in a to-and-fro oscillatory manner to design a systems-based ethical game.