The aim of this study is to investigate the academic achievement of 6th grade students in grammar course gamified with an online tool and their opinions regarding the application. The study employed quasi-experimental design and a semi-structured interview was utilised to obtain the qualitative data. The application lasted for 6 weeks during which the experimental group received gamified grammar education whereas the control group received content-based language learning. Pre-test and post-tests were applied to both groups to check if there were any differences between the scores. Since the quantitative data were not parametric, Wilcoxon Matched -- Pairs Signed Ranks Test and Mann Whitney U Test were used in the analysis of the data. Also, a semi-structured interview was utilised to learn about the opinions of the students in experimental group. The results yielded a significant difference in favor of students who received gamified grammar learning. The results were also supported by the positive opinions of the students towards gamification of grammar with an online tool as an in-class material.