X-Git-Url: http://winboard.nl/cgi-bin?a=blobdiff_plain;f=whats_new%2Frules%2FJanus.html;h=30606d5ff5605dd4ee6d451dc9a3c91889cc3cff;hb=d783e0c4dab936f6f07cc2cf38d97c617d6c3488;hp=b23131ec6e0b366c892a308e795139ec920a61ea;hpb=4d5a9416969353d11450b39b3b1403405098472a;p=xboard.git diff --git a/whats_new/rules/Janus.html b/whats_new/rules/Janus.html index b23131e..30606d5 100644 --- a/whats_new/rules/Janus.html +++ b/whats_new/rules/Janus.html @@ -1,390 +1,461 @@ - -

-Janus Chess - - -

- -

Janus Chess

- -	- Initial setup - -e1, e8: King - -f1, f8: Queen - -b1, b8, i1, i8: Janus - -a1, a8, j1, j8: Rook - -d1, d8, g1, g8: Bishop - -c1, c8, h1, h8: Knight - -a2-j2, a7-j7: Pawns - -

+ + Janus Chess + + + + + -

Moves at a Glance

Janus Chess

Click on a piece below to see its moves

+ + + -

+ +

Initial setup

e1, e8: King
+ f1, f8: Queen
+ b1, b8, i1, i8: Janus
+ a1, a8, j1, j8: Rook
+ d1, d8, g1, g8: Bishop
+ c1, c8, h1, h8: 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

Sliding capture or non-capture,
+ can be blocked on any square along the ray

-Unblockable leap (capture or non-capture) -

-Non-capture only -

Unblockable leap (capture or non-capture)

-Capture only -

Non-capture only

Capture only

- -

:
:
:
:

- -

-Piece -	-ID -	-value -	-Moves (Betza notation) -	-Remarks -
-King -	-K -	-- -	-K -	-Can castle with Rook, moving 3 or 4 steps to b- or i-file -
-Queen -	-Q -	-9.5 -	-RB or Q -	- -
-Janus -	-J -	-8.75 -	-BN -	- -
-Rook -	-R -	-5 -	-R -	- -
-Bishop -	-B -	-3.5 -	-B -	-Color-bound -
-Knight -	-N -	-3 -	-N -	- -
-Pawn -	-P -	-1 -	-mfWcfF -	-Promotes to Q, J, 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 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 to the square neighboring a Rook that has not moved before, -in which case that Rook is moved to the square next to the King on the other side. -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.

Differences with FIDE

-The Janus pieces are extra, and the board is expanded to accomodate them. -The King starts on the other side of the Queen. -Castling is asymmetric; the King moves 4 steps on long castling, 3 steps on short. -

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 Janus 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 Janus is nearly equal in value to Queen, under-promotion to it is common, -and there is virtually never any need to promote to R, B or N. -

-The super-pieces (Q, J) devaluate by the presence of lower-valued opponent pieces. -As a result trading Q for R + B is in general a good trade when you still have both J, -as the latter gain in value by eliminating the opponent's R and B, -which is more compensation than the intrinsic value differene between Q and R + B. -

+ + + + + + + + + + + + + + + + + + + + +

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

:
+ :
+ :
+ :

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Piece	ID	value	Moves (Betza notation)	Remarks
King	K	-	K	Can castle with Rook, moving 3 or 4 steps to b- or + i-file
Queen	Q	9.5	RB or Q
Janus	J	8.75	BN
Rook	R	5	R
Bishop	B	3.5	B	Color-bound
Knight	N	3	N
Pawn	P	1	mfWcfF	Promotes to Q, J, 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 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 to the square + neighboring a Rook that has not moved before, in which case + that Rook is moved to the square next to the King on the other + side. 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.

+ +

Differences with FIDE

+ +

The Janus pieces are extra, and the board is expanded to + accomodate them. The King starts on the other side of the Queen. + Castling is asymmetric; the King moves 4 steps on long castling, + 3 steps on short.

+ +

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 Janus 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 Janus is nearly equal in value to Queen, under-promotion to + it is common, and there is virtually never any need to promote to + R, B or N.

+ +

The super-pieces (Q, J) devaluate by the presence of + lower-valued opponent pieces. As a result trading Q for R + B is + in general a good trade when you still have both J, as the latter + gain in value by eliminating the opponent's R and B, which is + more compensation than the intrinsic value differene between Q + and R + B.

+ +