Superchess

Captured and substituted pieces will be displayed beside the board for promotion choice

Initial setup

The setup is not fixed, but created by randomly picking substitutes for four pieces of the FIDE array from a predetermined set. This substitution starts from the FIDE array:

e1, e8: King
d1, d8: Queen
a1, a8, h1, h8: Rook
c1, c8, f1, f8: Bishop
b1, b8, g1, g8: Knight
a2-h2, a7-h7: Pawns

Substitutes set I (Dutch Open Championship)

1 Amazon
1 Empress
1 Princess
1 Veteran

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	Can castle with Rook, moving 2 steps towards it
Queen	Q	9.5	RB or Q
Rook	R	5	R
Bishop	B	3.25	B	Color-bound
Knight	N	3.25	N
Pawn	P	1	mfWcfF	Promotes to any other piece that was captured or substituted
Amazon	A	12.25	QN
Empress	E	9	RN
Princess	S	8.75	BN
Veteran	V	7.5	KN

Pawn peculiarities

Pawns capture differently from how they move (straight move, diagonal capture).
Pawns can move two squares straight 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 or substituted pieces when they reach last rank. The chosen piece is then removed from this set.

Castling

A King that has not moved before can move two squares in the direction of a Rook that has not moved before, in which case that Rook is moved to the square the King skipped over. This is only allowed if all squares between King and Rook are empty, when the King is not in check on the square it came from, and would not be in check on any of the squares it skipped over.

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. You can use the New Shuffle dialog to control the randomization of the initial position.

Differences with FIDE

The start position contains four unorthodox pieces. Promotion only to pieces that were captured before (or substituted).

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.

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.