## 3 Results
### Study Characteristics
Despite the fact that all studies presented post-measures and evaluation data, only 25% (N = 11) performed any follow-up evaluation, varying from 1 week [94] to 6 months [73]. Data about the site being used in the studies demonstrated 16 cases (36%) that took place at participants' houses, 34% (N = 15) studies used laboratory conditions, 6 cases used schools, three were online, 1 study used a hybrid model with house and laboratory choices and another study used an assisted living facility. Regarding the devices being used, computers (PC/Laptop) were the major device, as reported in 52% of studies (N = 23), followed by tablet/smartphones devices (N = 17), and 2 studies used both computers and tablets [73; 77]. Only one study used a portable console (Nintendo Switch) [74], and 2 studies used a Virtual Reality set [63; 101]. Regarding the GEs being used in the 44 studies, a minimum of 2 elements per study were used [64; 77] with a maximum of 8 elements [75; 76]. The mean value of GEs used was 5.7 elements. The elements that were used the most were Conflict (88.63%; N = 39), Feedback (84%; N = 37), Progression (75%; N = 33), Difficulty Adjustment (73%; N = 32), Action Points (73%; N = 32) and Levels (70.45%; N = 31). Looking at GEs in more detail, and regarding the sample that was applied, starting with children and adolescents (N = 16; 50% were children with ADHD, autism spectrum disorder and visual perception delay), the most commonly used elements were Conflict and Feedback (N = 16), followed by Levels (N = 14), Action Points and Progression (N = 13 respectively) and Difficulty Adjustment (N = 12). On the other hand, Competition and Cooperation were underused (N = 3). Modality via PCs dominated (N = 13), followed by smartphones/tablets, and variations between study sites was balanced (Home 37.5%, Laboratory 31.25% and School 31.25%). Moving on to studies with adults (N = 13; 54% high-risk participants, suffering from multiple Sclerosis, schizophrenia, MCI and drug addiction), the most prevalent GEs were Conflict (N = 12), Difficulty Adjustment, Progression and Feedback (N = 10) and Action Points (N = 8), and the most underused were Competition and Cooperation (N = 1) and Avatar (N = 3). Again, computers and smartphones/tablets were the most commonly used devices (N = 5 respectively). However, there was one study that offered both devices (computers and tablets) [73], and a study used a portable console [74]. Laboratory interventions seemed to be the case here (N = 7), and houses were the next one (N = 5). There was a study with a hybrid model using a hospital and in-house sessions [90]. Finally, the GEs that were used the most in elderly studies (N = 15; 80% healthy, 20% patients with MCI) were Conflict, Feedback and Action Points (N = 11 respectively), Progression and Difficulty Adjustment (N = 10, respectively) and Narrative Context (N = 7), and Competition and Cooperation as well as Avatars were used less (N = 0, N = 1, N = 1). Interestingly, in the case of the elderly, tablets/smartphones dominated the devices (N = 10), with only 4 studies using computers (N = 4), and a single study offered both options [77]. Home interventions were the majority of studies (N = 9), and there were only 3 laboratory interventions. Moreover, there was a study that was conducted in an assisted living facility [87].