These are the rules that were specified in the Middle Shogi Manual:
A piece that has not yet promoted may, should the player choose to do so, promote at the end of any move that was at least partially within the promotion zone. That is, the piece started inside the promotion zone, or moved into the promotion zone.
A variation on the traditional rule about forbidding re-capture of a Lion by a non-Lion after the opponent's Lion was captured by a non-Lion, is to allow it if the Lion being captured is not protected. This was written in "Chu-Shogi Shinan Sho", 1703. A professional player Shimei Okazaki and self-styled great master Shoichi Masuda wrote this rule.
Protection is judged at the beginning of the move (as witnessed by the hidden protector rule). So a Lion that is only protected by a Pawn or Go-Between cannot be captured by a double move involving the capture of the protecting piece.
The following is a proposal for a repetition rule that is hoped will have the ideal characteristics.
The basic rule is that a player may not make a move that would leave the opponent viewing a position that the opponent has seen before in the same game.
However, if a player is in check, that player is not restricted in choice of move by the repetition rule.
Players should be able to agree to a draw, to avoid unnecessary prolongation of the game. Computer programs should provide a mechanism for proposing and agreeing to a draw. The rules for a particular tournament might restrict when a draw can be offered (e.g. not until 100 moves have been played).
I propose the following rule to prevent a game dragging on too long:
If 60 moves (30 moves by each player - a pass counts as a move) occur with none of the following occurring, then the game is declared a draw:
- A piece is captured
- A piece promotes
- The promotion distance for at least one of the players significantly decreases
I propose the following wording for a sensible bare-king rule:
The moment that one player has only a King or a Crown Prince left on the board, that player loses the game.
H.G.Muller isn't in favour of having a bare-king rule at all. His reasoning:
- In essentially drawn games, the result should be a draw. Not a win for one side
- It should not be necessary to play hundreds of moves to determine if a game is drawn or not.
- A decisive outcome (a win for one side or the other) is preferable to a draw. Therefore we need a rule to prevent repetition.
The question has been asked if it would be a good idea to establish a World Chu Shogi organization, with the aim of agreeing to, and promoting, a common set of rules.
My opinion is that we should first see if it is possible to come up with a consensus on what would be a good set of rules. So I am exploring the issue in this HTML book.
Mumyo_hosei has attempted an English translation of the rule here. Both the English used, and the amount of detail are obscure in places. This article is an attempt to formulate the rule rigorously.