**3.2 What games have been used in MI-based BCI?**

In this study, we refer to the book written by Ernest [30] to classify different games. The seven main genres are action, strategy, role-playing, real-world simulation, construction and management, adventure, and puzzle games. Additionally, we use subgenres for a better description. This subgenres classification strategy is also agreed by Ernest, who claims the classification change constantly with different circumstances.

Thus, this review develops a subgenre classification for the chosen 28 MI-BCI games depending on three aspects of the graphical interface: ① whether it is the firstperson view, ② which visual type (2D, 3D, VR) it is, and ③ what the game content type is. For content-type differentiation, this paper pays strong attention to task-orientate separation, i.e., what targets the gamers are asked to achieve, or what functions they are expected to present. Games with these similar contents would be linked. For instance, one study [31] describes itself as a cue movement game. Nevertheless, the game aims to pick a falling parachutist via a controllable platform. These contents, such as control method, feedback, and mission, are similar to the game [23], whose participants attempt to control a failing ball to land on a fixed basket. Thus, we identify the saving parachutist game as a ball-to-basket (B2B) game but not a cue movement-based searching coins game [32] (**Table 6**).

After game classification, four genres with 11 subgenres of MI-BCI games have been identified (see Appendix 1). We present each research group with its summarized game content type in this detailed form. In Appendix 1, the game vision type is shown. For easy understanding, we match both the content and vision of the games with the abbreviation (Ab.).

*Improving the Brain-Computer Interface Learning Process with Gamification in Motor Imagery:… DOI: http://dx.doi.org/10.5772/intechopen.105715*


**Table 6.**

*An example of game differentiation.*


#### **Table 7.**

*Four genres total score, number of studies and average score.*

The four main genres of MI-BCI games are action, puzzle, adventure, and simulation. **Table 7** presents the quality of each genre. The following paragraphs explain each genre with its typical subgenre games in order.
