Hajiku Shogi

Hajiku Shogi (弾(はじ)く, Flip Shogi) is inspired by and a love letter to Shogi and in particular Chu Shogi, an amazing game which all fans of chess should play.

'Hajiku' is Japanese for 'flip'. Both players control pieces that have the capability to flip to their opposite side when they reach the furthest three ranks, changing how they move.

Thank you to my good friend Casey Hill for his feedback and help playtesting the many iterations of the game, including simplifying the rules, without which this would be a very different and less fun game to play.

Setup

The interactive diagram is there to demonstrate the movement of pieces and does not enforce any other rules except for promotions.

Pieces

All of the pieces used are a subset of the pieces used in Chu Shogi. If you have a Chu Shogi set, you only need a board to play.

Both players start with four promoted pieces on their side of the board.

Standard

The King (K) moves one square orthogonally or one square diagonally. It does not promote.

The Gold General (G) moves one square orthogonally or one square diagonally forward. It promotes to a Rook.

The Silver General (S) moves one square orthongonally forward or one square diagonally. It promotes to a Vertical Mover.

The Copper General (C) moves one square vertically or one square diagonally forward. It promotes to a Side Mover.

The Ferocious Leopard (F) moves one square vertically or one square diagonally. It promotes to a Bishop.

The Pawn (P) moves one square orthogonally forward. It promotes to a Tokin. It must promote upon reaching the last rank.

Promoted

The Rook (+G) moves any number of squares orthogonally. It demotes to a Gold General.

The Vertical Mover (+S) moves any number of squares vertically or one square horizontally. It demotes to a Silver General.

The Side Mover (+C) moves any number of squares horizontally or one square vertically. It demotes to a Copper General.

The Bishop (+F) moves any number of squares diagonally. It demotes to a Ferocious Leopard.

The Tokin (+P) moves the same as the Gold General. It does not demote.

Rules

The aim of the game is to capture the opponent's King. As in Shogi, checkmate is sufficient to win the game as a player would normally resign before that would happen.

Flip Zone

Like the promotion zone in Shogi, both players have a flip zone at the furthest three ranks. Because both sides of pieces have different movements, 'flip' can be used to describe both promotion and demotion and 'flip zone' is used instead of a promotion zone for pieces.

To flip a piece, players move their piece into the flip zone and flip; move their piece while it's in the flip zone and flip; or move their piece out of the flip zone and flip. This all happens in a single move.

When a piece has moved out of the player's flip zone, it must move back into the zone to be able to flip after that turn.

There is no limit to the number of times a player can potentially flip a piece while on the board.

Pawns do not have the ability to flip. As in Shogi, they promote and when captured, they demote.

Counter-flip

One disadvantage can occur when a player makes a capture and demotes on the same turn. If the opponent recaptures, they get a weaker piece in exchange, even if it was the same type of piece.

To remedy this, whenever a piece makes a capture and demotes on the same move, the next player can capture that piece and optionally re-promote said piece 'in hand' on the same turn.

Counter-flips can only be done on the move after the demotion was made, similar to 'en passant' in chess. A piece that demotes without capturing can't be counter-flipped.

Drops

Pieces and pawns can be captured and put into hand to be dropped onto the board on future turns. Pieces you capture become yours to command. This is the same as in Shogi.

Pieces stay the same when they're captured without flipping in hand, except for when they are counter-flipped.

Pawn drops have the same restrictions as in Shogi. You may not drop a pawn onto a file with a friendly unpromoted pawn; onto the last rank; or to deliver checkmate.

Pawns always demote when they're captured.

Draws

As in Shogi, draws are possible. These include repetition of position four times (without check) and impasse: both kings enter their opponent's camps and are not at risk of checkmate.

Impasse is a complicated subject in Shogi and the piece values from Shogi do not make sense in Hajiku as the ability to flip changes them, nor Chu Shogi due to the different board size.

If a situation does occur where both kings have entered their opponent's first three ranks, I suggest that a draw is automatically declared after 50 half-moves from the move when the second king enters unless a checkmate occurs.

Players can agree to a different rule for impasse if they both consent before the start of the game.

Illegal Moves

As in Shogi, an illegal move loses the game.

As an option for playing over the board for amateur and friendly games, I suggest the following:

With both players' agreement, a game can continue after an illegal move if it involves a pawn drop. The dropped pawn is captured by the opponent simply by touching it and is added to their hand. The player who made an illegal move then makes another move.

A digital client would only allow legal moves so this situation wouldn't occur.

Notes

Notation

Notation is as in Shogi with the following change:

A flip is represented by a '+' at the end. For example, if Black wants to promote a Gold General on 5d to a Rook, they can play G-4c+. Then to demote the Rook back to a Gold General, they can play +G-4i+. The next move can be G-3h.

A counter-flip is represented by a '!' after the 'x' when capturing. For example, Black moves their Vertical Mover from 1i to 1a, capturing a Side Mover and demoting to a Silver. This would be written as +Sx1a+.

White recaptures with the King and counter-flips the Silver back to a Vertical Mover in hand. This is written as Kx!1a.

Tips

Openings are slower than in Chess, giving you a chance to prepare, but faster than in Shogi. Castle your king with step-movers in defence before exchanging a large number of pieces.

Promoted pieces can struggle to checkmate as there are no pieces that promote to a gold general, only pawns. Use tokins to restrict the king's movement and co-ordinate with other pieces.

Under attack? Sometimes the best defence is a counter-attack! Cause your opponent to doubt themselves as any attack on your position could then give you more material to further attack their king.

The ability to flip opens up new opportunities. Experiment with chaining drops and flips to steadily weaken your opponent's position.

Design

The game started to take form in 2019 with experiments with combining different pieces into one similar to Micro Shogi, for example: rook/bishop; queen/knight; vertical mover/side mover; gold/silver.

Originally a player could flip at will but that was found to be too powerful. Pawns kept their promoted form when captured but it became awkward when they were used for defence and it was simpler just to have them demote instead.

The board was originally 8 by 8 and later became 7 by 9. The design took shape when focus was placed on the vertical mover and side mover and on minimising the number of piece moves needed to learn the game.

From there the game took shape and was mostly complete in late 2020 and published in 2021 with minor changes.

Last revised by Edward Webb.