## 4 Discussion
Automatic speech-recognition systems would allow the assessment of reading aloud [66], but this technology is still challenging [67] due to its limited reliability [67; 68; 69] and the difficulty in considering the variety of human speech and background noises [68; 69]. Therefore, this may be a challenge in the future. The results of the studies included in the present systematic review highlight that children with reading impairments benefit from digital-game-based reading training. The studies generally have a low risk of bias in all the domains investigated, except for the absence of outcome data in [32]. Furthermore, the experimental groups in the reviewed studies benefited exclusively from SG training, and no further classic face-to-face rehabilitation training with the operator was provided in support. Therefore, the effectiveness of training with SGs was proven even on its own. All the studies in this systematic review found a significantly higher improvement in reading skills among children trained with SGs compared with the control group, although this was sometimes evident only in the most difficult conditions. This was probably due to the already discrete performance in easy conditions, as well as to the high consistency of the orthographies of the languages spoken by the children in the studies. It should be noted that the training using SGs was performed for an average of 6 weeks, with six weekly sessions of about 20 min. This highlights that very short and undemanding training might succeed in achieving satisfactory results by children with reading and spelling difficulties/disorders, at least in the first years of schooling. However, the lack of a follow-up prevents us from drawing a conclusion as to the long-term effects of SG interventions. In this regard, further studies are needed. The experimental group did not improve more than the controls in spelling and text comprehension (except for one study, in reading comprehension), indicating the poor generalization of progress to untreated skills. The SG training did not have a significant impact on untrained literacy skills. Therefore, due to the different deficits associated with each literacy skill, different methods targeting the specific symptoms are needed [70; 71; 72]. Reading comprehension is effectively a different skill, which is also based on linguistic and inferential processes [73]. However, the lack of generalization of the effect of reading training on spelling outcomes is surprising. Several studies show strong parallels between reading and spelling performance, with item-specific difficulty in both tasks [74; 75; 76], as well as common deficits underlying reading and writing difficulties [75; 76; 77; 78; 79; 80]. Moreover, several studies have demonstrated spelling improvements after reading training as a carry-over effect [81; 82; 83]. However, this research was on lexical learning and spelling, while the SGs in this systematic review focused only on sublexical processing. Therefore, SGs based on lexical reading training may be likely to generate greater carry-over effects on lexical spelling (and vice versa). In any case, according to the results of this systematic review, it is evident that SG training should be complemented by modules specifically targeting reading comprehension and spelling skills. The results show that the SGs were perceived as having adequate difficulty levels, user friendliness, and task explanation by children and significant adults. This is an important finding because a level of higher learning improvement was reported for SGs that are perceived as useful, easy, and uncomplicated, and fun and enjoyable [84]. These characteristics guarantee the feasibility of independent SG training in home environments, with online notifications of children's training progress. Thanks to the innovative features of SGs, such as their adaptivity, immediate feedback, and reward, the training does not need an external instructor.