Ah, mais oui, l'usage français! Perhaps we ought to refer to George Duke as Georges Duc from now on! No, only joking.
The point on colouring is an interesting one - although I could not see any actual rules about what the square colours signify in Chess on the Rainbow. Of course most colourings would eventually render the game something like Pied Chess in appearance, if not necessarily in rules. One exception would be making every face the same standard odd-side board - making the choices of cube 3x3x3, 5x5x5, 7x7x7 et cetera.
Central Rotation Chess seems a necglected game. An anticlockwise version would be very different due to King/Queen assymetry, and might be worth considering as a subvariant.
The point on colouring is an interesting one - although I could not see any actual rules about what the square colours signify in Chess on the Rainbow. Of course most colourings would eventually render the game something like Pied Chess in appearance, if not necessarily in rules. One exception would be making every face the same standard odd-side board - making the choices of cube 3x3x3, 5x5x5, 7x7x7 et cetera.
Central Rotation Chess seems a necglected game. An anticlockwise version would be very different due to King/Queen assymetry, and might be worth considering as a subvariant.