In recent years there has been a renewal of educational software encouraged by the incorporation of specific designs based on serious games. Previous studies on their use do not provide conclusive data on the advancement in learning, both at a general level and in specific contents. The main objective of this work is to study the impact of the use of serious games in primary education classrooms, specifically on mathematics fluency, taking into account gamification variables and teaching experience. A quasi-experimental study was carried out with a pretest-posttest design, without a control group and with several experimental groups, involving 284 students from the first to the fourth grade. The results show a significant improvement in mathematics fluency with the use of serious games in the different grades and classroom groups studied. The gamification strategy promotes even greater progress over the classes where it has not been implemented. There is a similar time of use of serious games by both novice and experienced teachers, with better results in mathematics fluency in the case of the second group. It also shows the relationship between the results obtained and the school grades of the students. The findings point to the potential of using serious games designed specifically for school environments and challenge previous work on generational barriers in teachers.