This study aimed to generate a grounded theory based on data that explains the reasons why high school teachers in Montevideo, Uruguay adopt or do not adopt active teaching tools with an emphasis on gamification. The methodology had a qualitative approach using Constructivist Grounded Theory. Through biographical interviews with teachers, the low use of active teaching tools was identified, with gamification being the least used. The category “fear of gamifying” stands out as the element that most broadly explains the above. The results show that although gamification has the potential to make learning more interactive and engaging, significant barriers limit its adoption. Among the main barriers are the lack of time to plan gamified activities, fear of losing control of the classroom, creativity requirements, pressure from colleagues and families who may not view these innovative methodologies favorably, and concerns about evaluation. Additionally, the research suggests that it is crucial to provide adequate teacher training and institutional support to overcome these barriers. The conclusion highlights the importance of self-evaluation and self-critique in the educational system, proposing that a reflective approach can help teachers overcome their fears and adopt new methodologies that benefit student learning.