It's kinda like that "conquer the world" feature they had on RA2 a long while back...
Basicly, a chess player controls a "territory", in this case, a board, and a list of ppl then challenge him/her. He takes turns facing them in the queue. The one controling presently is the "defender", and he plays black, the attacker, plays white. If the defender wins, he keeps the board/territory, if the attacker wins, he conquests that territory and faces the next one on the queue, in the next game, he will be the defender.