The 2014 EU Directive on Maritime Spatial Planning (MSP) lays down obligations for the EU Member States to establish a maritime planning process, resulting in a maritime spatial plan by 2020. Consultation should be carried out with local, national and transnational stakeholders. Stakeholder engagement in MSP is complex because of the great number and diversity of maritime stakeholders and the unfamiliarity of some of these stakeholders with MSP and its potential impact. To facilitate stakeholder engagement in MSP, the 'MSP Challenge' table top strategy game was designed and played as part of several stakeholder events in different European countries. The authors study the efficacy of the game for stakeholder engagement. Background and evaluation data of nineteen game sessions with a total of 310 stakeholders with different backgrounds were collected through post-game surveys. Furthermore, the efficacy of the game for stakeholder engagement processes, organised by competent MSP authorities in Scotland and Belgium, is studied in more detail. The results show that the board game, overall, has been a very efficient and effective way of familiarising a great diversity of stakeholders with MSP and to create meaningful interaction and learning among stakeholders in formal planning processes. However, the case studies also show that contextual factors-the level of familiarity with MSP and participants' perception to sustainability-influences the efficacy of the game.