Gamification has been studied in the context of English as a foreign language (EFL) teaching as an intriguing approach, and its impact on language skills and motivational states of learners has been an area of interest; however, further experimental and qualitative accounts on the matter are still required. Additionally, the construct of 'self' as a rather novel outlook for motivation has been explored by merely a handful of studies. This study aimed to determine the effects of gamified instruction on high school EFL learners' motivation and motivational 'self' systems. To achieve this, the study employed an explanatory sequential mixed-method research design to make sense of learners' motivational states and L2 selves. Quantitative data collected through motivation and L2 self scales were interpreted with the consideration of qualitative data obtained from a focus group session. The results of the study revealed promising outcomes in terms of motivation to learn English as the modules increased the willingness of learners to learn English to communicate with other cultures, and they regarded English as a part of a well-rounded education. Moreover, they started to doubt their "self" constructs regarding being more knowledgeable in the English language in different dimensions. Finally, the study concluded with some crucial points regarding the effectiveness of gamified language learning settings, and recommendations were made for future research.