Table 2 Inclusion/exclusion criteria

1

The learning environment must involve digital educational games. Studies using game elements in non-game environments (e.g., studies on gamification) were excluded

2

Research topics were STEM education, including science, physics, chemistry, biology, mathematics, technology and engineering education

3

The research type should be experimental or quasi-experimental design. Studies without a control/comparison group were excluded

4

The comparison types between the experimental group and the control group were digital educational games and non-educational games (for inclusion in the first meta-analysis), or basic digital educational games and digital educational games with added game mechanics (for inclusion in the second meta-analysis). Other studies that compared game genres and did not isolate the effect of games were excluded

5

There were sufficient statistical data in the research report to allow calculation or estimation of effect size between the comparison groups (e.g., sample size, mean value, standard deviation, T value, F value, etc.)

6

The study participants were students, excluding those with learning disabilities

7

The language of published studies should be English