by Edward Lovett
Essentially, play is as per FIDE chess, although special rules pertain to capturing. Main playing area is a board comprising 5 x 8 squares; attached to this board is the reenterent square, via which the most recently captured piece has the possibility of reentering play. A special bishop move is also available, which allows a bishop to switch to the alternate coloured squares. As might be expected, pawns promote upon reaching the eighth rank, and winning is accomplished by checkmating the opponent.
Squares are alternately coloured dark and light. Initial piece placement is as shown. Note the square to the right of the main playing area; this is the reenterent square.
Click here for a photo of a prototype
playing board with initial piece placement (jpeg 12k).
On capturing an opponent's piece, the piece is placed on the reenterent square by the player doing the capturing, displacing a piece, if any, already on that square.
II. REENTERING A PIECE FROM THE REENTERENT SQUARE
A piece on the reenterent square may possibly 'escape' from capture and return to battle according to the following rules. Note that only the player who initially owned that piece may possibly return it to play - that is, there are no defections in this variant.
A piece on the reenterent square may be returned to play if:
1. It is that players turn to move.
2. The player is not in check; if in check, a piece from the reenterent square may only be reentered if it can block the check (subject to rule 3 below). A reenterent piece cannot capture a checking piece.
3. There is an 'appropriate square' to return the piece to; all pieces attempting to escape try to find their way back to base camp as a means of orienting their way back into battle. An 'appropriate square' is defined as the square it initially occupied at the start of play, or a square it may have legally moved to on its first move. There is an additional constraint in that such a square must also be vacant.
A few notes follow that may help clarify some points of play. Note particularly rules for reentering a pawn.
III. REENTERING PIECES - Notes
Let Black capture White's knight; the white knight is placed upon the reenterent square by Black, concluding Black's move. Now, assuming that White is not in check, White may return the knight to any of d1 (the square it originally occupied) or to either c3 or e3, squares to which a move is available to the white knight at the start of play, provided the chosen square is vacant.
White is under no compulsion to return the piece to play. He may have a forced mate, for instance, or a sound combination that will return a piece of greater value. Of course, in this latter instance, he will lose his knight as it will be displaced from the reenterent square. If desired, and provided no captures have taken place, the knight may be returned to play at any time by White, subject to the reenterent rules above.
Perhaps you are wondering if a piece may be returned to play, and by virtue of the position, give 'check' at the same time: happily, the answer is yes (all the more glory your return to battle!). You may also block a check to your king, or thwart mate, should the position present itself (provided of course, rule 3 is not violated).
Note that the queen, bishop and rook may only be returned to play on their original respective squares, as they have no other legal move available to them at this time. This implies that if any of these pieces are captured on their original squares, or are captured elsewhere and any piece is occupying their respective initial squares, then they cannot be immediately returned to play; by virtue of this, a player whose piece is so captured will be somewhat limited in replying to other threats or combinations as any piece they capture, for example, a pawn, will displace a piece already on the reenterent square, say possibly their queen.
With one additional constraint, a pawn on the reenterent square may also be returned to play provided the three reenterent rules (above) are not violated; a pawn may only be returned to an open file (that is, a file (column) that does not already contain a pawn of the same colour). It need not be the file from which it was captured. Note that, theoretically, all pawns have at least three moves available for reentry - the initial square occupied at start of play, and the square one step or two steps forward from this square, these squares being moves which are legally available to the pawn at start of play.
Since a pawn can reenter on any open file, it may possibly have several 'starting squares' and forward moves from which to choose. Pawns returned to an initial square (that is, on rank 2) regain their initial (optional) two move step - we may think of it as a consequence of the terrain, in that the battlefield slopes down in this area and it is thus possible to make more progress.
Let us consider one possible scenario: the pawn on b2 has
been captured on its original square and there are no other
pawns of the same colour on that file and the position is
quiescent. Further, an opponent's pawn is situated on b3.
Can the pawn captured on b2 (now sitting on the
reenterent square) be returned to play on b4?
Yes - pawns may sneak by the enemy when reentering their own camp. Any square that a pawn may have initially occupied, or could have moved to from such a square, provided it is vacant (and the file contains no other pawn of that colour), is a contender for reentry. Note that, depending on positional factors, it may be desirous to reenter the pawn captured on b2 to another open file.
For the record, a pawn reentered onto rank 2 and then (at some time) proceeding to a 2 square forward move, may be subjected to en passant capture.
Castling is permitted and rather unique, and is not for the faint-hearted. Castling exposes the king centrally, and the rook practically crosses the back rank in the process. All FIDE criteria for castling is assumed and will not be repeated here.
Think of this move as a special pathway through the camp that the king may negotiate with an aide under the cover of darkness. Rather than a 'move to safety' as in FIDE chess, this move is more surprising in nature, demonstrating more than anything the 'boldness' of the king as he blatently enters the fray.
To formalise this procedure, the king moves from its initial square to that of its bishop's initial square; the rook is then moved to the queen's initial square, constituting a 'single move', as per FIDE rules. Remember, all normal rules for castling apply.
V. SPECIAL BISHOPS' MOVE
At the beginning of play, the players bishops are on the alternate coloured squares; given the chance they will happily glide around the board and 'never the twain shall meet'. In 'usual' chess, if you only have one bishop, that bishop can only ever exert control over half the total squares. Not so in reenterent chess. Men of the cloth (the bishops) knoweth of the ancient catacombs beneath the squares c4 and c5 whereby they may switch to the alternate coloured squares.
Any time a bishop moves to one of the squares c4 or c5, it may switch to the other square, if that square is vacant, as the conclusion to its move. Whilst it immediately gets control over these alternate coloured squares (that is, may possibly give check, or threaten a piece) it cannot continue moving until the opponent has moved.
Admittedly, this move is hard to make when the board is crowded with pieces, but provides a measure of extra strength to the bishop towards the endgame.
The special bishops' move is entirely optional, but if not made immediately, requires a separate move to accomplish. Thus, a bishop sitting on c5 may move to c4 in one turn. A bishop moving to c5 may finish their move on c4 (provided, in both instances, c4 is vacant). Remember, no other piece knows of the catacombs; this special move is only available to bishops.
AFTERWORDReenterent Chess was devised as an entry in the 41-squares chess variant design contest 2001, to mark the occasion of Hans Bodlaender's 41st birthday.
Written by Edward Lovett.
WWW page created: March 2, 2001.