Yes NIP-64 it defines one event, which is the outcome of a game after it is played. It could be used as a game in progress too, but that requires clients to understand chess logic and to interpret algebraic notation, so I'm proposing FEN which allows clients to remain dumb and still play chess. And NIP-64 doesn't have any way of pairing people together for a game, reporting errors, dealing with draws or resigning, timing, etc. My proposal adds more parts but still is far from complete.