Shogi on Jocly

Description

Shogi (将棋 shogi, "general's game") is the Japanese version of Chess. It is famous for its drop rule, which lets you return pieces you capture to the board under your control.

Find out more on the dedicated page on chessvariant website.

https://www.chessvariants.com/shogi.html

Rules

Shogi (Japanese Chess)

Shogi is the Japanese cousin of Chess. Very similar to it in some respects, it differs from Chess mainly by allowing players to keep captured pieces and replay them as their own. To win you have to checkmate the king of your opponent.

Board

The board is a 9x9

Pieces

for each team:

1 King
2 Gold generals
2 Silver generals
1 Bishop
1 Rook
2 lances
2 Horses
9 Pawns

Initial setup

We made a western set of pieces for players who might not be familiar with the traditional japanese version.

Pieces actions and properties

Gold general: moves and captures to adjacent squares in any orthogonal or the forward diagonal direction.

Silver general: moves and captures to adjacent squares in any diagonal or the forward orthogonal direction.

Pawn : The Pawn: moves and captures to the square directly in front of it.

Rook : as in chess.

Bishop : as in chess.

King : as in chess.

Knight : The Knight has the two forward-most moves of the Chess knight.

Lance : The Lance moves as a Rook but only forward in the same file, never sideways or backward.

Promotions

Pawn, Lance, Knight, and Silver general promotes to Tokin, Promoted lance, Promoted knight, and Promoted silver, respectively, all of which move like a Gold general.

Rook and Bishop gain king move upon promotion to Dragon king and Dragon horse, respectively.

The promotion zone is the farthest three rows of the board, and a piece may promote if part of its move touches the zone. Promotion is optional unless no subsequent move is possible otherwise. So a Pawn or Lance must promote on the last row, and a Knight must promote on the last two rows.

The King does not promote, nor can already promoted pieces promote further.

Drops

Captured pieces become prisoners and lose their promotion, guarded on your right. You can use your turn to put them back into play. A player can either move one of his pieces or drop a prisoner back into play on his behalf.

A Pawn can’t be dropped on a column with an unpromoted Pawn of the same color.

A Pawn can’t make an immediate checkmate when dropped. It is allowed for other pieces.

A piece can’t be dropped is no subsequent move is possible, so a Pawn or Lance cannot be dropped on the last row, and a Knight cannot be dropped on the last two rows.

Available skins

2D skins are available for all, 3D skins need WebGL so please use Chrome or Firefox.

Credits

Jocly implementation

Rules and descriptions : A. M. DeWitt
Development : H.G.Muller (TalkChess)
Graphics : F. Houdebert

Comments

Shogi. Play the Japanese form of Chess with Jocly.

A. M. DeWitt wrote on Fri, Jan 26 09:53 AM EST in reply to H. G. Muller from Thu Jan 25 09:55 AM:

I tested this description of the bug, and that looks to be exactly right. Would switching lines 142 and 143 help?

Also, does updating this require updating both the browser cache and CloudFare's cache in order for changes to show?

Edit: I also tested this with the other drop games. The bug also appears in Tori Shogi (Three Swallows instead of Two Pawns) but not in Mini Shogi.

📝H. G. Muller wrote on Thu, Jan 25 09:55 AM EST in reply to A. M. DeWitt from Wed Jan 24 11:50 AM:

I did notice a bug in the drop-model, but not one that explanes exactly what you describe. The wrapper of cbApplyMove does demotion and testing for Pawn capture in the wrong order (lines 142 and 143). With as consequence that capturing a Tokin decreases the Pawn count for the file where it happens. So it should not matter in which file you promoted, but depend on where the Tokin was captured. As the Pawn count is updated incrementally, the error would persist for the rest of the game.