Serious games are instructional tools that harmonise different pedagogical approaches and pursue specific behavioural and learning outcomes. Characterised by flexibility and complexity, serious games can draw from a vast number of elements and game mechanics. We argue that such adaptability requires specific pedagogical competencies from designers to avoid using game elements counterproductively for user learning. The literature shows lack of studies based on this perspective: if the influence of single instructional techniques has been studied, the impact of pedagogical expertise is missing, and this represents the knowledge gap this study intends to bridge. This paper reports on an experimental study of a serious game that is part of a course in Industrial Systems Engineering. Through collaborative efforts between an engineering professor and a pedagogical expert rooted in neuroeducation and syntheses of meta-analyses tied to learning achievement, the serious game was redesigned. This pre-test-post-test control and experimental group design study investigates how designers' pedagogical competencies can impact learning outcomes, motivation, and decision-making processes. The pedagogically revised serious game outperforms the original one in motivation and, in specific subgroups, in learning performance, highlighting the importance of combining pedagogical and engineering insights.