Low coral islands are heavily dependent on groundwater for freshwater supplies. The availability, quality, and management of groundwater are central to sustainable development and poverty alleviation in many developing small island nations. The declaration by the Government of Kiribati of water reserves on the atoll of Tarawa, over privately owned land, has lead to conflicts, illegal settlements and vandalism of public assets. Beside, the water consumption per capita tends to increase towards western-like standards, threatening the sustainability of the actual exploitation system. Finally, pollution generated by the 45 000 habitants of South Tarawa has already contaminated all the freshwater lenses, with the exception of the existing reserves so far. Our project, called AtollGame, aims at providing the relevant information to the local actors, including institutional and local community representatives in order to facilitate the dialogue and devise together sustainable and equitable water management practices. Multi-Agent Based Simulations (MABS) coupled with a Role-Playing Game have been implemented to fulfil this aim. They have the potential to greatly reduce conflict over natural resource management and resource allocation. In order to collect, understand and merge viewpoints coming from different stakeholders, the following 3-stage methodology is applied: collecting local and expert knowledge, blending the different viewpoints into a gamebased model, playing the game with the different stakeholders in order to explore different scenarii and their simulated outcomes. Although game sessions delivered successful outcomes, the final stage of the project is characterised by the upheaval of contradictory Government stands that undermine the whole process. It is argued that heterogeneous viewpoints may be handled in a satisfactory manner during the gaming sessions, but that longterm hidden agendas may override the outcomes. Beyond the inherent question of legitimacy at