Philidor said that the soul of Chess is Pawn structure. If I replaced Pawns with pieces that move like a Pawn or a Knight, the Knighted Pawns would just wipe each other out, and Pawn structure would play no role in the game. If I was to create a game without Pawn structures, which is what I did do, I wanted to replace them with something that serves a similar function. I did that by replacing Pawn structures with Cavalier structures. To do this, I replaced Pawns with Chinese Chess Knights, which are called Cavaliers in this game. The Cavalier moves like a Knight in Chess but cannot jump pieces. So, when two Cavaliers of opposite color move out to the same file, they block each other, sort of like Pawns block each other when they do the same thing. This blocking of Cavaliers by each other allows for the creation of Cavalier structures, which make it dangerous to venture over to the opponent's side of the board. Part of the game in Chess is about breaking through your opponent's Pawn structures. In Cavalier Chess, it is about breaking through your opponent's Cavalier structures. If the soul of Chess is Pawn structure, the soul of Cavalier Chess is Cavalier structure.
The Pawn's double move and en passant capturing were introduced into Chess to compensate for the Pawn's otherwise impoverished ability to move. Cavaliers are naturally more powerful than Pawns and do not need special moves. So they have none.
After playing a game where the Queen had a Knight's move, I decided that it made the Queen too powerful and destroyed the playability of the game. So I decided to leave the Queen as she was in Chess. Doing this also provides a link of continuity with modern Chess. Modern Chess, originally known as Queen's Chess, greatly enhanced the powers of the Queen. Cavalier Chess enhances the powers of the remaining pieces.
In Chess, castling protects the King and develops the Rook. In Cavalier Chess, the Knight King is better at defending himself and escaping his pursuers than the King in Chess is. The Knight King is also more useful than the Chess King for getting into the fray and attacking other pieces. Secluding the King, which is what castling does in Chess, would prevent the King from helping out on the battlefield. Moreover, the Marshall is easily developed without castling, and since the Marshall is developed so easily and Pawns are replaced with Cavaliers, a Knight King could easily be in more danger near the Marshall's file than in his own file. So, Cavalier Chess lacks the circumstances which make castling helpful in Chess, and more often than not, castling could hurt a player's game. So I have chosen to leave castling out.
In Chess, a Pawn may promote to any superior piece besides the King. In Cavalier Chess, a Cavalier promotes to the piece whose starting square it lands on, except for the Knight King, which it can't promote to. When it lands on that square, it promotes to any other superior piece of the player's choosing. I made promotion work this way, because Cavaliers have more freedom of movement than Pawns have in standard Chess. This extra freedom of movement gives you more choice about where to land your Cavalier on the eighth rank, and you can choose what piece you want to promote to by directing your Cavalier to the appropriate square. The advantage to doing promotion this way is that it enhances gameplay. It does this by providing one more thing for the two players to struggle over. When your opponent can't stop you from landing a Cavalier on the eighth rank, he can still try to stop you from promoting to the best piece you can. This extra point of conflict should make the game more interesting. Another reason for doing promotion this way is that Cavaliers are swifter than Pawns and may reach the eighth rank sooner. Restricting promotion like this can help prevent the game from becoming too unbalanced too early.