Exchess® is played by the Laws of Superchess®
One can play Exchess® with only a few new pieces, combined with the well-known chess pieces, on an ordinary 8x8-chessboard.
Rules of play for Exchess® on an ordinary 8x8-chessboard:
In the starting position of ordinary chess, White replaces as desired one or more pieces on the Kings wing with the same number of new pieces. Black makes the symmetric substitutions and next Black replaces as desired one or more pieces on the Queens wing with the same number of new pieces. Subsequently White makes the position symmetric again. After this phase of the prelude White makes the first move and the game is played on like chess.
Pawns may be replaced only with different pawn pieces (rapid pawns or t-pawns), and other pieces only with non-pawn pieces. At least one monarch (King or Emperor) must be deployed. Emperors start on the d-file, Kings on the e-file.
The rapid pawn and the t-pawn promote in the same way as an ordinary pawn does, to a non-pawn piece. At the promotion one of the available pieces (not on the board) must be chosen.
The two players decide beforehand by agreement which set of pieces will be available in the prelude and during the game (for the promotion and for deploying as reserve pieces), and how many new pieces White and Black, respectively, may or must deploy in the prelude.