Hello @mister_cole and thank you very very much for your comment. It is extremely useful to express different opinions not taking anything for granted. I love this topic and I’m happy to discuss it at any opportunity 
The paper you mentioned says also
The study suggests that gamification can effectively improve the attitude of undergraduate students of medical sciences towards learning statistics.
I would consider it a good output.
There are also books that follow this line
and several whitepapers that confirm that gamification can enhance student learning outcomes. For example:
- https://www.researchgate.net/publication/334083351_Exploring_the_impact_of_gamification_on_student_engagement_and_involvement_with_e-learning_systems
“Exploring the impact of gamification on student engagement and involvement with e-learning systems”
The abstract says probably what we are looking
In spite of the unprecedented popularity to use innovative gaming concepts within the educational context in order to promote active learning, engage people and solve motivational problems, there is an emerging body of research work arguing that gamification is not effective to increase neither the student’s engagement nor the learning outcomes. In this research paper, an empirical study is conducted to explore how gamification can firstly affect the student learning engagement and the interactivity level with e-learning technologies.
and in the conclusion
For the impact of gamification on the engagement, motivation and uptake for using e-learning technologies, the empirical results have revealed considerable positive impact for students who have made large contribution on the platform in terms of published content and accumulated scores.
- The Gamification of Learning: a Meta-analysis | Educational Psychology Review
“The Gamification of Learning: a Meta-analysis”
This paper has an insightful conclusion
The initial question was whether gamification is effective for learning. The results from the present meta-analysis suggest that, yes, gamification might in fact be effective when it comes to learning. However, the question of which factors contribute most to successful gamification remains partly unresolved, at least for cognitive learning outcomes
- Unlocking potential: Systematic review the use of gamification in leadership curriculum | Education and Information Technologies
“Unlocking potential: Systematic review the use of gamification in leadership curriculum”
I wanted to find something about the adult learner to try to contract your assumption that “I would expect even less effect in non-compulsory settings with adult learners.”
In the section “4.5 Outcomes of implementation” it says
Studies demonstrate that gamification provides a real-time learning tool that allows participants to engage with complex issues effectively (Olsen & Abildgaard, 2022; Padilla et al., 2022). Additionally, it significantly enhances student engagement, task orientation, and motivation (Durrani et al., 2022; Tay et al., 2022).
- https://trepo.tuni.fi/bitstream/handle/10024/104598/gamification_of_education_2018.pdf?sequence=1
“Gamification of education and learning: A review of empirical literature”
Probably the best literature review I found is this one which catalogs 128 empirical research papers in the field of gamification of education and learning. It concludes the study with a clear
the results reported in the reviewed studies are strongly positively oriented
[about gamification].
- The impact of gamification on students’ learning, engagement and behavior based on their personality traits | Smart Learning Environments | Full Text
The impact of gamification on students’ learning, engagement and behavior based on their personality traits
We have found evidence that gamification affected users in distinct ways based on their personality traits. Our results indicate that the effect of gamification depends on the specific characteristics of users.
Yes, you are not alone in having doubts about the effectiveness of learning through gamification. I honestly took it for granted because probably the narrative was strong in these years. This paper was enlightening. Thanks for planting the seed of doubt in me.
Your comment allows me to dig and learn. I hope that overall you like my project.
Anyway, I invite you to open another conversation about how in this solution teachers can gain much deeper insight into students’ knowledge by examining their confidence in the right answer.
I look forward to hearing from you again.
Thanks,
Mario