Over the years, the marine contracting sector has faced many challenges surrounding safety, the economic fluctuations because of the oil crisis and now tackling the sustainability challenge. Years of experience in the offshore industry, a heavy industry that contributes significantly to the climate crisis through its environmental impact, is deemed to change its strategy and way of working. However, this challenge is relatively new and asks for a new approach to move along with the fast-changing requirements of clients and external regulations that can have financial consequences if one is not acting now. Engineering solutions to reduce and prevent impact are already aligned, thinking of shore power, carbon capture and storage techniques, and alternative fuels on the vessels. Nevertheless, the total environmental impact goes beyond the implementation of these technologies. Making a change on the total impact of a marine contractor asks for a behavioural change within the organization, towards decision-making taking care of the environment. Finding a balance in actions that lead to investing in sustainable technologies and setting every employee to actions that flourish within to contribute to the company's sustainability ambitions will help improve their environmental performance. This research explores how to stimulate and support sustainable behaviour within project scope in a marine contracting organization through designing a suitable intervention. This intervention combines the design principles discovered with theories from gamification. From creative thinking and exploring the different means of gamification in a sustainability context, gamification was chosen as a suitable format for the intervention. The objective of the intervention is to stimulate people to think of sustainable solutions in their work by making them aware of environmental impact and actions. More important, it is a fun and interactive introduction to highlight the contribution one has to the total environmental footprint of the company. The game is designed to be played by project teams that start with the project's conceptual design phase within a marine contractor organization. The game's purpose is to become aware of the environmental impact indicators and actions and to share individual values by deciding what investments to make in reducing the impact of the fictitious project. Players are challenged during the game to make strategic decisions to design their fictitious wind project that will have an as low as possible environmental impact. This is to make sustainability and environmental impact more tangible for the project team and ensure that employees can start discussions on sustainability within the marine contracting industry from a common ground and experience on sustainability.