It is evident that a lot of inconsistencies exist among research reports on the effect of games on mathematics achievement of secondary school students in Nigeria. This study was to integrate the results of the previous studies on games and mathematics achievement carried out in different parts of Nigeria, in order to arrive at a generalized conclusion. This study was guided by three research questions and one research hypothesis. The population of the study consisted of all the previous research reports on games and mathematics achievement in Nigeria. The purposive and snowball sampling techniques were used to gather the studies that constituted the sample. In all, twenty-six studies which included journal articles, Ph.D theses, M.Ed, B.Ed and PGDE projects, were integrated. Data was collected using a validated and reliable coding instrument designed for the study. In data analysis, descriptive statistics, statistical transformations and effect sizes were used to answer the research questions, while Winer combined test was used to test the hypothesis. The result of this study revealed that the accumulated results of the previous studies showed a positive and statistically significant effect of games on secondary school students’ mathematics achievement. The findings of the study also revealed that games have moderate effect on mathematics achievement in secondary schools. The study has implications for curriculum planners and teachers. Based on the implications and findings, it was recommended that workshops should be organized on the use of game facilities for the improvement of mathematics teaching and learning in our schools.