How do the ratings on the Fortunes page affect the game?
Global ratings of players have no effect on the game itself; they do, however, give you an idea as to the quality of the opponent you’ll be facing. There is a very specific algorithm involved in calculating ratings, which I won’t bother getting into here; suffice it to say that the higher a player’s rating, the more skilled he is. Games can either be “rated,” in which every player must fall within a certain rating range in order to play (to keep the level of challenge more constant among the players involved), or “open” games, which have no rating limits, and which can also be a rather jarring experience for new players. You have been warned.