Too late! Most of the games I haven't played in your list have been fighting games (which I'm not interested in) or Nintendo games (my first Nintendo system were a GBA & DS... in something like 2010).

EDIT: If I were you, though, I'd wait to see if I've played the games you put in your top 20 rather than worrying that I haven't played what you feel is the 50-somethingth best game you've ever played.