The number of science, technology, engineering, and mathematics (STEM)-related jobs is increasing all around the world and especially in Europe. However, teachers face many difficulties in making STEM related classes more attractive and motivating the students to learn. This paper presents two case studies involving 116 students from two European countries (Slovakia and Ireland). The studies investigated the impact of a new educational computer game called Final Frontier on learning process and students' motivation. We found that there are no significant differences between the two countries in terms of students' interest in STEM, although the students in Slovakia achieved slightly better grades than those in Ireland. We also found that in both countries, the students using the Final Frontier game outperformed those not using the game in improving their subject knowledge after the study. Furthermore, the impact of game-based learning on students' motivation for STEM differed in the two countries.