That's interesting if you wanna get the pairing right, but the probability of USA vs USA is only 3,6% and I won't rely on that. USA vs. Germany is the best choice in my opinion, since it's way more probable to guess one of both nationalities right, if you choose different ones.
If you assume the best tactics is to pick to nations, it is not clear from the demographics that USA vs Germany would be the best choice. It is possible that due to the games Polish people choose compared to Germans that the latter play less against US-citizens than the former....
Well, I don't really care about pairings, because it's unlikely that you guess it right and it doesn't really matter whether you choose Germany vs. USA or Poland vs. USA. Both cases are extremely rare.
I would try to get the single point by chosing the two countries with the largest number of active players. Well, the 8% of Polish players might be more active than the 9% of German players... this would matter indeed.
But it's more about luck than tactics anyways :P
If it's 19.0% and 9.0% then all else being equal, the odds are actually better of USA vs. Germany than US vs. US. You have double the chance of being right when you pick different countries, because either country can come first. (2 permutations per combination.) And double 9.0 > 19.0.
As a greedy American, I feel I must spoil the fun here. Points? I MIGHT get POINTS for all my hard work? Where's the MONEY bay bay. Where's the numbered Swiss account. Where are my chips and dip? That's where it's at. It's hard work dodging butterflies. The observer influences the observed through the act of observation. And what about fake nationalities. Someone might time their own game to land on the desired URL, set up an obscure nationality, bet the long odds, and take us all to the cleaners! We need robot police. You have to think these things through.
My guesses for what game it will be:
1.Go
2.StreetSoccer
3.Chess
And who will win the game?
I predict the first player. (The player who interacts with the board first, whether the interaction is a "move" or not. E.g. the player making the initial placement in Polyomino, the player who chooses a set of tiles in Wyps numeric)
Dvd might still be right, because of rounding. For example, If 19% US is actually 18.51% and 9% Germany is actually 9.49%, then 2*9.49% is 18.98% which is greater than US actual.