Maybe double elimination, whatever works best, but would be fun
#Chess Tournament
solemn torrent
solemn torrent
In a different format, could do a king of the hill kind of game where the person who wins stays, and another chatter replaces the old loser. To make sure that the one who wins isn't there forever due to elo disparity, maybe they keep the time they had when they won the last game so it turns into trying to win as many as you can without spending too much time. A win could result in +30 seconds or something.