Archchess

This early Chess variant was proposed by Italian Chess scholar Francesco Piacenza in his book I Campeggiamenti negli Scacchi as Arciscacchiere, and then given its English name Archchess by John Gollon in an unpublished book on Chess variants. The game is played on a board of 10x10 squares. In addition to the usual Chess pieces and two more pawns, each player also has one centurion, starting in the fourth column, and one decurion, starting in the seventh. The centurion jumps to any square two squares distant, either in a straight line or changing direction like a knight. The decurion moves a single square in any diagonal direction, like the fers of Shatranj. The options and restrictions regarding promotion, castling and en passant are slightly different from regular Chess and/or slightly ambiguous. For instance, pawns are promoted when reaching the last row and always promote to queens.