Existing pedagogical approaches to ethics education in engineering and science reinforce what this paper terms "the fallacy of the individual decision-maker" by suggesting an oversimplified, individualistic model of ethical decision-making, rather than recognizing the organizational, cultural, or group deliberative context of an ethical dilemma. Consequently, students fail to develop the group deliberative and ethical reasoning skills necessary to properly recognize and resolve ethical questions. This paper critiques existing approaches and presents an alternative pedagogy that emphasizes active, participatory, and experiential learning that is intended to more deeply immerse students in questions of fairness, justice, and equity in the context of sustainability by playing the Externalities Game. Preliminary testing supports the hypotheses that game play results in deeper consideration of ethical issues, more emotionally engaged students, fosters greater deliberative discourse, and encourages experimentation with different ethical strategies. The Externalities Game may be an appropriate piece of a larger course in sustainability ethics when combined with traditional reading and pedagogical strategies.