My population of interest would fall around High School Sophomores.  The age group would fall under 15-16.We would recruit them from class based on how well do in geometry. If they were not doing well, like really struggling then we would advise them to try something fun like the game that is being invited.

The students that have a 75% or higher on their test don’t need to play the game if they don’t want to. The students are diverse so there is no favoritism or singling out. The get motivate because they would probably get motivated from wanting to do better or earning a certificate saying you did excellent.