Contemporary secondary technology education often does not mirror engineering practice. While there is much rhetoric on the need for promoting active, authentic, and real-world professional experiences in upper secondary school, most technology education teaching remains traditional, and teacher centered. This study investigates the affordances for authenticity of role-play-based project work in a Swedish upper secondary software engineering course. The project required students (aged 17-18) to assume the role of software engineer employees at a web-design business with the task of creating a website for a gaming company, where the course instructor assumed the role of the web business owner. The six-week project included the formulation of a design plan, back-end programming, developing and refining the design and layout, adjusting content for accessibility, and publication of the web site. Inductive analysis of observations from the unfolding role-play in five student groups (total 22 students), and interviews with four students and the teacher exposed salient themes related to authenticity of the role-play-based project exposed within teacher-student interactions and student intragroup interactions. Teacher-student interactions revealed that the teacher exhibited various roles in the project, initially acting as a customer but also the responsibilities of a boss and a teacher-mentor. In the latter instance, students perceived the project as more school-oriented than authentic, expressing a preference for an external customer, and at the same time, the teacher tried to align the task with the project's curriculum requirements. Student intragroup interactions showed that despite highly varied roles, students felt that their assigned roles enhanced the authenticity of their experience, although they were unaware of what a real scenario might entail. Successful students emphasized the importance of structured work and clear responsibilities to meet the project goal. The findings show that while role-playing is not necessarily always equivalent to reality, it was viewed as a fulfilling and situated learning experience that simulated a real-world scenario, but which relied on mutual confidence and responsibility between the role-players. Future work will combine the findings with existing frameworks of authenticity to inform the development of role-play scenarios in upper secondary engineering education.