.... corrected
Are you an X1 who plays Tremulous?
Actually, that would be xxx-ist because it would be implying that X1 inherently acts differently from Y1. However, it is xxx fact that X2 and Y2 are different.
so what is the difference?
(Nice rephrasing.) How can I explain the differences of differences clearly? Delta-delta.
Do I really need to explain the differences between men and women?
Do I really need to explain the differences between one complexion and another? It is similar to asking how many attractive or ugly people play Tremulous. Those are both subjective and irrelevant.
If, however, it were found that 999 out of 1000 Tremulous players were white, that might be concerning. In that case, it would be useful to know how many black people play.
From a purely statistical standpoint, it is known that more males play computer games than females. If Tremulous's statistics do not correlate with those of other computer games, what is Tremulous doing right or wrong?
Other than that, it shouldn't matter. (But it is psychological fact that people act differently with different groups of peers. If they consider a member of a different race differently from a member of their own race, that is probably the result of racism.)