If you have three players, but only a single regular Chess set, you can take turns playing one pair, then another, etc. However, someone is always sitting out. Triune Chess is a scheme that allows all three players to play at the same time.
The game is played by the usual rules of orthodox chess, except for who moves which pieces. The sequence of turn and color is as follows:
Turn Player A Player B Player C 1. White Black White 2. Black White Black 3. White Black White ... ... ... ...Or, to put it using the more usual turn sequence:
Turn White Black 1. Player A Player B 2. Player C Player A 3. Player B Player C 4. Player A Player B ... ... ...A player who makes a mating move, wins the game.