**2.3 Study selection**

Three main types of criteria have been used in this review: Selection Criteria (SC), Exclusion Criteria (EC), and Inclusion and Quality Criteria (IQC). SC is for broadly filtering articles. After determining the scope of literature via SC, EC will determine this scope more precisely. IQC is adopted to decide whether the articles could be suitable after deep reading. The specific SC, EC, and IQC can be seen below:

## *2.3.1 Selection criteria*

For objectiveness, the chosen articles must be written in English. Furthermore, these articles must be peer-reviewed, covering a designed MI-BCI game. There is no restriction for the published years as some early MI-BCI game systems, such as the first-person shooting game [24], are still highly valued in the academic area.

