This study aims to examine what effects computer games have on English L2 learning and better: what factors in computer games are key for these effects to occur. The study also examines what playing computer games can do for the students’ communication skills and linguistic competences. This study is a literature study in which older studies have been analysed to give answers to the research questions. The results in this study show that playing computer games can improve communication skills and linguistic competences such as vocabulary, sociolinguistic competence and strategic competence. The results also show that playing computer games online has a better effect on English L2 learning than playing computer games offline.