Grand Chess

Captured pieces will be displayed beside the board for promotion choice

Initial setup e1, e8: King d1, d8: Queen f1, f8: Chancellor g1, g8: Archbishop a0, a9, j0, j9: Rook c1, c8, h1, h8: Bishop b1, b8, i1, i8: Knight a2-j2, a7-j7: 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)
											Non-capture only
											Capture only

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Piece	ID	value	Moves (Betza notation)	Remarks
King	K	-	K
Queen	Q	9.5	RB or Q
Chancellor	C	9	RN
ArchBishop	A	8.75	BN
Rook	R	5	R
Bishop	B	3.5	B	Color-bound
Knight	N	3	N
Pawn	P	1	mfWcfF	Promotes to any other piece that was captured

Pawn peculiarities

• Pawns capture differently from how they move (straight move, diagonal capture).
• Pawns can move two squares ahead from their initial position, provided they are not blocked.
• On the move immediately after such a double push, they can be captured en passant by another Pawn, as if they had only moved 1 square ahead.
• Pawns promote to a piece chosen from the set of captured pieces when moving in or into the promotion zone.
• The Promotion zone consists of the last three ranks.
• When arriving on last rank, promotion is mandatory. On other ranks it is optional.
• If no promotion piece is available for a mandatory promotion, the Pawn cannot be advanced.

General rules

• It is not allowed to expose your King to check.
• The game is won by checkmating the opponent's King.
• Stalemate (no legal moves, but not in check) is a draw.

XBoard interface issues

When a Pawn can be promoted, XBoard first advances it as a Pawn to the promotion square. Then it waits for you to complete the move entry by clicking on the piece in the holdings beside the board that you want to promote to. To defer promotion you can click on a Pawn or on an empty square in the holdings of the promoting side.

Differences with FIDE

The Chancellor and Archbishop pieces are extra, and the board is expanded to accomodate them. There is no castling. Promotion only allows you to regain back a piece that you lost before. The promotion zone is 3 ranks deep, and promotion is only mandatory on last rank.

Strategy issues

It is not possible to force checkmate on a bare King with just a single Bishop or Knight (in addition to your own King). Two Knights cannot do that either. The Archbishop can force checkmate against a bare King.

Bishops are confined to squares of a single color. Having Bishops on both colors compensates this weakness, and is worth an extra 0.5 on top of their added value.

As Chancellor and Archbishop are nearly equal in value to Queen, under-promotion is very common.

The super-pieces (Q, C, A) devaluate by the presence of lower-valued opponent pieces. As a result trading Q for R + B is in not as bad when you still have A and C, as the latter gain in value by eliminating the opponent's R and B, which is more compensation than the intrinsic value difference between Q and R + B.