Catan® (1995) is a multiplayer tabletop game with global sales of over 20 million copies. Presented here is an exploration of the steps that were taken in the development of the Catan: Global Warming expansion, from prototype to final design. During the playtesting of the game the feedback that we received from a variety of playtesters indicated that the game mechanics (rather than any accompanying story) were an effective and elegant way of developing dialogue around a specific topic, in this instance global warming. We conclude that in order to develop such a game, consideration must be given to: the accessibility of the game, the game literacy of the proposed players, the playtesting of the game mechanics, the peer review of the scientific content, and the extent to which the metagame (i.e. those discussions that take place around and away from the game) is enabled.