Mathematical_Recreations-Kraitchik-2e

~78 Mathematical Recreations
the like. This upsets the initial balance of forces so that the
later course of the game is usually different from that of a
game begun with balanced forces.
Certain moves may be made obligatory. Some other modifications
of the rules are:
The Marseille game, in which each side plays two moves
in succession.
The Legal game, in which White uses eight extra pawns
instead of the queen.
The marked-pawn game. A pawn, usually the king's
knight's, is marked, say with a paper cap. If this pawn is
captured its owner loses the game. He can also lose by being
checkmated in the usual way, but he may checkmate his adversary
only with the marked pawn, which may not be
moved to the eighth row and exchanged for another piece.
Such odds can only be given to a very much weaker opponent.
'Ve enter the domain of fairy chess proper only by the introduction
of new pieces whose moves are defined. The best
known pieces of this sort are the following, introduced by
Dawson:
The alfil - actually an earlier form of the present bishop.
Like the bishop it moves along diagonals in any direction,
but must land just two squares away, whether or not the
intervening square is occupied. From Q3 it may go to KB!,
KB5, QKtl, or QKt5.
The jers, which moves one cell at a time on the diagonals.
A fers that results from the promotion of a pawn that has
reached the eighth row may also jump one square in any direction,
orthogonal or diagonal.
The dabbaba, which moves in the orthogonals as the alfil
does in the diagonals.
The chancellor, which combines the moves of the knight
and rook.