Background: Game-based science learning (GBSL) provide an alternative route for learning genetics, but its effects on students' conceptual learning is contested. In this paper we assess the utility, in primary teacher education, of Recal - a game designed to promote participants' learning of key genetic concepts through acting as detectives investigating a case. Purpose: The purpose of the study was to analyse and compare teacher students' learning of genetics through the game, and both their attitudes towards and experiences of it. Tests were conducted in Spanish and Swedish contexts to assess its potential utility in contrasting cultural and educational contexts to obtain indications of the potential breadth of its application. Samples: Participants included 120 pre-service teacher students from a university in north-eastern Spain and 51 from a university in western Sweden. Design and methods: The research involved an intervention, in which students played the game, and assessment of its efficacy by questionnaires designed to investigate students' knowledge of genetics before and after the game, their expectations and experience of it, and their satisfaction with it. The results were analysed statistically. Results: The game appeared to enhance both Spanish and Swedish participants' knowledge of genetics, and they reportedly found it both educationally beneficial and engaging. It was also assessed in terms of the following characteristics of GBSL, based on experiential data: contextualisation, authenticity, collaboration, problem-solving, guided paths and competition. Conclusion: The results clearly indicate that the game has utility in different countries and educational contexts. The article discusses how the six characteristics of GBSL facilitate or hinder learning, and implications (for educational professionals and researchers) of the findings.