In this paper an educational design proposal is presented which combines two well established teaching approaches, that of Game-based Learning (GBL) and Content and Language Integrated Learning (CLIL). The context of the proposal was the design of an educational geography computer game, utilizing QR Codes and Google Earth for teaching English Language to Greek Primary School students. This integration provides a motivational and cognitive basis for language learning, since it represents a meaningful, contextualized activity and on the other hand, gives students the chance to expand their cognitive skills and use more sophisticated language. The proposed game immersed 11 to 12-year-old students in problem solving challenges regarding the use of geography in realistic contexts. While attempting to solve these problems, students were engaged in eight-week collaborative work, involving six levels of gameplay by following hints, provided by QR codes images. The findings of this case study suggest how foreign language learning can successfully take place within a geography game-based learning environment, and they underscore the efficacy of approaching GBL in terms of performance. Students' performance was evaluated through knowledge tests and various complex tasks throughout the game play, involving writing and reading skills. In general, students showed positive attitudes towards the game and the post-test results have significant differences compared to those of the pre-test, in terms of vocabulary acquisition and reading skills in the foreign language and geography knowledge. The results also showed that the collaboration required by this game, allowed the students to interact in a controlled environment, where they undertook roles and responsibilities. To this end, the findings will make an important contribution to the empirical evidence of GBL particularly with regards to its application in primary education.