It was actually better than a perfect game. Galarraga got 28 guys out in a row — the first time anyone ever legitimately got more than 27 out without anyone reaching base. You could make an argument, on this basis, that this was the best single-game pitching performance in MLB history.
There was an extra-innings perfect game, but it was way long ago. Memory fails me, but I bet someone comes along and tells us the team, pitcher and year. This is FR.
May 26, 1959, Harvey Haddix of the Pittsburgh Pirates pitched 12 perfect innings against the Milwaukee Braves, retiring 36 consecutive batters before losing the game in the 13th inning when it all ended on an error, an intentional walk of Hank Aaron then a double............