Designers often use scenarios to approach complex design problems holistically. Efficient use of scenarios can be a challenge in complex dynamic user contexts due to mediation and tool limitations that use traditional scenario techniques in design practice. We investigate the use of real-time 3D game engines on the part of interaction/product designer-researchers as a design tool to conceptualise and simulate possible future shared user scenarios in the maritime domain. Three exploratory and qualitative case studies are presented, drawing on collaborative and participatory design, action research, and research through design. Results reveal that real-time 3D game engines can simulate multiple complex behaviours that otherwise would have been impossible to materialize with traditional visual scenario or storytelling methods. This opens up new possibilities for how designers can handle complex user relations and related risk factors when designing. For the maritime sector this has further potential for the handling of safety critical operations.