The premise behind Cavalier Chess is that most pieces have horses, and the game represents a cavalry battle between two feudal kingdoms. Cavalier Chess uses different pieces than Chess, but each piece starts off in the same place as its counterpart in Chess. In Cavalier Chess, the Knight King (K+N) replaces the King, the Marshall (R+N) replaces the Rook, the Paladin (B+N) replaces the Bishop, the Nightrider (multiple N moves) replaces the Knight, and the Cavalier (XiangQi N) replaces the Pawn. The Queen is the same as in Chess. Unlike standard Chess, there is no castling. When a Cavalier reaches the eighth rank, it promotes to the piece whose starting square it lands on. A Cavalier cannot promote to a Knight King, and if it lands on the Knight King's starting square, it promotes to another superior piece of the player's choosing.

For more information visit Fergus's webpage on Cavalier Chess. Fergus also has created some Cavalier Chess mating problems, which is a separate download.