Cylinder Chess

Initial setup

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

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	-	oK	Can castle with Rook, moving 2 steps towards it
Queen	Q	11	oRoB or oQ
Rook	R	5	oR
Bishop	B	4	oB	Color-bound
Knight	N	3.25	oN
Pawn	P	1	mfWcfoF	Promotes to Q, R, B, or N on reaching last rank

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 another (non-royal) piece of choice when they reach last rank.

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

The board wraps around like a cylinder, the h-file connecting to the a-file.
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

Cylinder Chess must be played with legality testing off, as XBoard does not understand the wrapping of the board.

Differences with FIDE

The board wraps around as a cylinder.

Strategy issues

It is not possible to force checkmate on a bare King with just a single Rook,Bishop or Knight (in addition to your own King). Two Knights and Bishops in any combination cannot do that either. (Because the board has no corners, forcing checkmate has become much more difficult.)

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.

The Rook and Knight hardly benefit from the cylinder board. The Bishop, whose moves normally often end on the left or right board edge, does benefit some, and a Queen gets very dangerous.