I checked my collection and I think it has to do with the language the game and manual are in. For instance: All my GC games have a blue triangle except Metroid Prime; the only difference between Metroid Prime and the other games? All the other games have the manual and cover text in Dutch except for Metroid Prime which has those in English.

__________________

Both this all inspiring signature and the incredible avatar were made by Leminnes' Silent Graphics
Potestatem obscuri lateris nescis!
Dido Florian Cloud De Bounevialle Armstrong