Chu Shogi (Ancient Japanese Chess)

Chu Shogi was already known in the year 1250, and has been the dominant form of Chess in Japan for many centuries. In recent time, after the invention of piece drops, it was overtaken in popularity by modern Shogi. It is still widely played in Japan, though.

Initial setup f0, g11: King f2, g9: Lion g2, f9: Queen (Free King) e2, e9, h2, h9: Dragon King d2, d9, i2, i9: Dragon Horse c2, c9, j2, j9: Rook c1, c10, j1, j10: Bishop b2, b9, k2, k9: Vertical Mover a2, a9, l2, l9: Side Mover a1, a10, l1, l10: Canon (Reverse Chariot) a0, a11, l0, l11: Lance f1, g10: Kylin g1, f10: Phoenix g0, f11: Elephant e1, e10, h1, h10: Blind Tiger e0, e11, h0, h11: Gold General d0, d11, i0, i11: Silver General c0, c11, j0, j11: Copper General b0, b11, k0, k11: Ferocious Leopard d4, d7, i4, i7: Cobra (Go Between) a3-l3, a8-l8: Pawns

Moves at a Glance

Click on a piece below to see its moves

											Sliding capture or non-capture, can be blocked on any square along the ray
											Unblockable leap (capture or non-capture)
											Captured while passing through the square to another destination

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sym	Piece name	ID	value	Moves (Betza notation)	Remarks
	King	K	-	K
	Lion	N		KADN(cK-aK)(K-bK)	Can move twice per turn (as King)
	Queen	Q		RB or Q
	Dragon(-King)	D		RF	Promotes to Eagle
	(Dragon-)Horse	H		BW	Promotes to Unicorn
	Rook	R		R	Promotes to Dragon
	Bishop	B		B	Promotes to Horse
	Vertical Mover	V		vRsW	Promotes to Narrow Queen
	Side Mover	S		sRvW	Promotes to Sleeping Queen
	Canon	A		vR	Promotes to Whale
	Lance	L		fR	Promotes to White Horse
	Kylin	O		FD	Promotes to Lion
	Phoenix	X		WA	Promotes to Queen
	Elephant	E		FsfW	Promotes to a second King
	Blind Tiger	T		FsbW	Promotes to Flying Stag
	Gold	G		WfF	Promotes to Rook
	Silver	S		FfW	promotes to Vertical Mover
	Copper	C		fFvW	promotes to Side Mover
	Ferocious Leopard	F		FvW	promotes to Bishop
	Cobra	I		vW	promotes to Elephant
	Pawn	P		fW	promotes to Gold
Promoted pieces (not initially present)
	Eagle	+D		RbBf(FA(cF-F)(mcF-bF))	Moves as Q, except for linear double-step 'stinging' moves diagonally forward
	Unicorn	+H		BsbRf(WD(cW-W)(mcW-bW))	(aka Horned Falcon) Moves as Q, except for linear double-step 'stinging' forward
	Narrow Queen	+V		BvR	aka Flying Ox
	Sleeping Queen	+M		BsR	aka Free Boar
	Flying Stag	+T		FvRsW
	White Horse	+L		vRfB
	Whale	+A		fbRbB

Pawn peculiarities

• Pawns move and capture straight ahead.

General rules

• The game is won by capturing the opponent's only King.
• Pieces promote at the end of a move into the promotion zone.
• The promotion zone consists of the last four ranks.
• Pieces promote only once.
• Perpetual checking is forbidden, and would be ruled a loss on the 4-fold repeat.
• Other repetitions lose for the side that creates them.

Lion moves and Stinging pieces

Some pieces can make two moves per turn. That means they can also capture two pieces per turn, one on the square they move to (as normal), and one 'en passant' on the transit square. They can also capture on the transit square, and move on to an empty square ('hit and run'), or capture and move back to where they came from ('shooting' the piece from a distance, as it were). Of course they can also capture a single piece in the normal Chess manner. In that case the transit square is immaterial.

The Lion can make such double moves as two King steps, i.e. in all directions, and arbitrarily changing direction between them. The Unicorn and the Eagle can only make double moves in one or two directions respectively. They can not arbitrarily change direction, but only reverse it (or not), so they do stay on the ray in that direction. But that way they can still make double, hit-and-run, shooting or normal captures. All these pieces can also jump over the transit square, i.e. reach the distant two-step destination in a single jump. Finally they can also just make a step to an adjacent square, refraining from taking a second step.

Restrictions on Lion capture

There are rules to make Lion trading very difficult, in order to keep the Lions in play. Basically they specify that two Lions cannot be captured in consecutive half-moves. When the first capture is Lion x Lion from a distance, it is forbidden to play it if recapture of the capturing Lion is possible. When another piece captures a Lion, it is just the other way around: then the 'counterstrike' by a non-Lion against the Lion is forbidden. One possibility left open is thus when you capture an adjacent Lion. But then you would in general be foolish to allow recapture, as you could take the Lion hit-and-run fashion, fleeing to a save square. An exception to the rule is when a valuable opponent piece (i.e. not a Pawn or Go Between) forms a 'bridge' between the Lions; you may then capture that piece in the first leg of the double-move, and then take the opponent Lion with the second leg. Then the opponent can recapture, but he will have lost a valuable piece.

XBoard interface issues

This game has to be played with the option Show Target Squares on! This option will cause marking of the target squares of any piece you select or grab, by the engine (with legality testing off) or by XBoard (legality testing on). Moving to a square marked in cyan will be interpreted not as the final destination, but as the transit square after the first step of a multi-leg move. XBoard will then highlight the possible destination squares of the second leg from there. Should you want to end on the cyan square, you click it again, (it will be no longer marked in cyan), and XBoard will terminate the move after the first leg. You can also move back to the starting square, to 'shoot' the opponent piece from nearby.

With Detour Underpromotion on, XBoard will assume by default that every piece that enters the zone promotes. Should you want to defer in this mode, you should use a click-click move, and when you make the click on the promotion square, move the mouse down before releasing the button. If you move enough the piece on the promotion square will change back to the unpromoted form, and then you can release. With Detour Underpromotion off, you will automatically get a promotion popup that asks whether you want to promote or defer.

Differences with FIDE

Except that there are also Kings, Queens, Rooks and Bishops, not much is the same.

Strategy issues

Piece with no sliding forward moves are hard to promote, but promotion of forward sliders is practically unavoidable.

You can have two Kings by promoting the Elephant, in which case the opponent would have to capture both in order to win.