The decline of fresh-enrolled students and the increase in the number of dropouts in electrical engineering schools might be related to motivation, engagement and differences in learning preferences. This paper provides a detailed description of the development, application, and evaluation of an online, asynchronous simulation game to teach electricity markets concepts named EMGA. The EMGA aims to introduce students to the short-term electricity market structure, highlighting the importance of forecasting tools for decision-making. The EMGA has been deployed in a Master's course with 27 students. The learning effectiveness was assessed with a survey at the end of the exercise. Questions aiming at experience generation, conceptual understanding, skills development and affective evaluation were enquired. Positive results towards experience generation, conceptual understanding and affective evaluation were obtained. Students felt optimistic about the platform's potential. The main complaints from students were their lack of programming experience and the allocated time for the exercise during the course. Results from this small test, along with previously obtained results, are encouraging and might be of potential use for further developing the EMGA and student's experience.