Quite a few -- too many to itemize -- when I went through all the games the first time for the "win every game once", sometimes I'd get an easy win because the other person didn't know the rules, or they would quit / time out or something and I'd just move on to the next game. But to get to 100 ELO in a game you have to "figure the game out" to some extent.
Sometimes there would be interesting emergent complexity that made a game more interesting, or I'd realize that the game was simply more "fun" than I remembered.
But it went both ways -- sometimes I'd realize that a game was pretty shallow or just "by the book".
