Someone mentioned card suits in one of the long lists above. Considering the name “Aces High”, card suits would be a nice play off of the title. You have Aces in all of the suits and no one suit has different connotation or functionality than any other. Color is generally irrelevant (unless your are playing something like solitaire) so you could assign any color. Number of countries? Pick any 2, 3 or 4.
BFD