[alexti]

I'd think that ranking of the standard games would not work well (due to possible pact and alliances). However 1x1 or team games (2x2, 3x3 etc) should work well. Essentially, the important requirement is to have only 2 parties at the start and one winning party in the end. As a ranking system, Elo rating system (like in chess) should work fine. In principle, there're only 2 main requirements for the ranking system to work. The total of Ratings of all participating players should not change after the game, and the increase of the rating for the win should be greater if one defeats stronger player. To extend the system for the teams, the total winnings should probably be divided equally bewteen the players in the winning team (the amount of winning would depend on relative total Ratings of opposing teams).