As alternative to IWRM, the Negotiated Approach is proposed to involve communities in groundwater management. This should increase water security in peri-urban Khulna, in Bangladesh. A serious game is desired to make the approach more accessible and support its collective learning process. With interviews, different parts in the process that required support were identified. By linking different game functions to the process, the desired function of mediation support was selected. A review of existing alternatives confirmed the feasibility of such a tool. Analysis of the situation in Khulna showed that awareness of interdependency, influence on the problem and the benefits of cooperation are desired learning effects. Because these cannot be enhanced by existing applications, a paper-based, multi-level, format in which all players extract water from the same bucket in order to achieve objectives, is proposed. Evaluations with experts and playtests show that the prototype is adaptable and playable with different player types. The game did succeed in enhancing perspective change and creating a notion of interdependency, but still lacks a clear cooperative goal and is likely too difficult to be played by local users. Because the game is designed outside its intended context, further development in Khulna is necessary.