Transcendental Chess of one side can be any of 4²×6!÷2² = 2880. There is no castling. On the first turn a player, instead of making a move, can transpose any of two pieces on the back row. In Chess960 the back rows are mirror images, but in Transcendental Chess the setup of black and white is different 2879 out of every 2880 times (there being a 1–in–2880 chance that both sides will draw the same setup). This can create inequalities in the position. One way to equalize these inequalities is to play a couplet: the players play two games, one each as
Pocket Mutation Chess chess. Instead of moving, a player can take one of their own pieces from the board and put it into the pocket, provided that the pocket is empty. If the piece is placed into the pocket from the last rank, it gets promoted to a piece of higher class. Otherwise the player has an option to mutate the piece into a different piece of the same class. The choice of mutating (or not) must be made at the time the piece is removed. White cannot use the pocket on the first move. The king cannot be placed into the pocket.