Fluidity Chess
I've created this variant for Lichess (free libre chess site with millions of players), but its developers currently don't embed new variants. So I've written it here.
The main source of inspiration is Atomic Chess, variant which's already on that site. I play it well btw.
Setup
Standard chessboard and setup.
Pieces
No one piece can move to an occupied square. Also pieces deliver check only on their move destinations (as they do in chess). Most of them capture by dissolving — going through all the opponent's pieces to the free square behind them when capturing them. By this, pieces can jump, but only to take. So it's possible to capture many pieces at once even if they were in row.
Pawn
- moves & checks as in chess:
- moves one space straight forward, can move two from start rank;
- checks opposite King if he is diagonally forward to it;
- is very cheap stepper and captures
- the piece which is one square sideways from it by bypassing — stepping one square diagonally, leaving this foe piece behind & deleting it from the board (exactly as en passant in Chess);
- the piece which is one space directly forward (if your pawn is on start rank) by going through it to next space forward;
- as very cheap stepper, can take only one piece per move;
- can't move through friendly pieces;
- can't take a piece which stands on opposite edge of the board;
- and promotes as in Chess, on the farthest rank to every piece but the King.
Bishop
- moves & checks as in chess, unobstructed diagonal line;
- is ranger and captures opposite pieces by going through them to any free square behind the farthest of them;
- as ranger, he can capture up to 3 pieces per turn (restriction is for all rangers, it isn't the most number of pieces can be taken, but tweak for prolonging the games);
- is colorbound;
- can't move through friendly pieces;
- and can't capture a piece which stands on the edge of the board.
Knight
- moves & checks as in chess, L-shape;
- is leaper and captures those pieces which are in 1 and 2 squares orthogonally in direction of this move (as we learn his moves, 2 squares straight in one side, 1 in other; and first 2 squares are under dissolving capture there);
- as leaper, it can capture up to 2 pieces per turn, and checks so differently than captures;
- is only piece whose capturing of foe pieces is optional;
- can jump over friendly pieces (without taking them);
- and can capture a piece which stands on every square, even on the edge or corner of the board.
Rook
- moves & checks as in chess, unobstructed orthogonal (straight) line;
- is ranger and captures by going through pieces to any free square behind the farthest one;
- can capture up to 3 pieces per turn;
- can't move through friendly pieces;
- can't capture piece which is placed in corner;
- but can capture a piece if it's on the edge of the board;
- and can capture during the castling (see later).
Queen
Bishop + Rook, she is ranger and can capture up to 3 pieces (which aren't on the corner) per turn; she can't move through friendly pieces.
King
As in chess, 1 square in arbitrary directions, can't move into check; but he doesn’t capture by himself because he can't go through (and by this, two kings can be near each other, due to being not in check. So you can checkmate or stalemate opponent’s king near your king by another piece(s)). Castling: you can castle if:
- your king and rook haven’t moved yet;
- your king isn’t under check;
- your castling path is free from your pieces & isn't under check;
- you have opponent’s pieces between king and rook, but not in row. (If you have foe pieces on b & d files, you can castle queenside yet).
and if you castle through them, you capture them — up to 1 piece by castling kingside, and up to 2 if queenside, and castling can capture only minor pieces, i. e. Bishops or/and Knights. (King can capture only during castling. By the way it's the only case when moving to occupied squares is legal, i. e. they firstly become unoccupied and then you step on them).
He is royal, but can't be captured by displacement, you simply should avoid check and prevent the dissolving of him.
Rules
Your aim is to checkmate the opposite King. However, stalemate is a loss of player without legal moves. You also can capture him by dissolving if:
- opponent will block the path of check after your move, and his King will be behind his own pieces (and behind the king will be free square(s));
- you can do it by your knight or pawn.
This move is always legal, even if you're in check (or unavoidable check). Same logic in Atomic chess - they can take your King but no one can give an order to do so. (This is why King can be called General).
Draw occurs if:
- only 2 kings (& 1 bishop) are left on the board (unless it's win in 1 when losing King is in corner, advanced one stands on adjacent diagonally square, and you move by Bishop to space near them both, and that's stalemate);
- there is 3-fold repetition;
- or there are 25 moves without checkmate/stalemate/capture.
2 kings and 1 knight endgame is not draw.
Examples
Let us think that all pawns are traded.
In this diagram, Rook on d1, Bishops on a4 & b2, and both Kings cannot be captured at this turn because there's no squares behind them (at least it's on directions which are possible at this turn). Circles show legal moves for white Rook on b4. It can move vertically (but not to b1 due to friendly piece on b2 blocking its path), but this isn't pleasant here. However, it can capture black's Knight on c4 and Queen on d4 at once (landing on e4), or take them with Bishop on f4 also (three pieces are permitted to be taken at once) landing on g4 and checking black King; so it's win in 3 for White (because King can't take and it will have to go h5 or h3, and Rook from d1 can come [back;)] to h1 and check also, so black must block it by moving Bishop to h2, so Rook from h1 takes both Bishop and King, landing on h file behind the King - there's no restriction to take two adjacent pieces if King went h3).
Also white can move by Bishop on b2 (which's pinned by the way and whose legal moves are shown on diagram above) to c3 (but it's not pleasant here) or to take black Queen, only (landing on e5 or f6) or with Knight on g7 landing on h8 (note that if there was black piece on e5 or f6 it could be taken also, but if there were two black pieces on these squares, that capture wouldn't be available at all: there would be more than 3 pieces); so this taking makes the unclear situation: initiative goes to black (Knight can take the Rook on b4 by going a3 with hidden threat to white King which should move b2 to save the game), but white Bishop is lucky and breaks their plans to win, with possibility for d1 Rook to 'dance' with black King for draw.
Also white can move by d1 Rook (also possibly capturing Queen with landing behind her) or by the King.
But if white does so or it's black's turn, this is won game for black. If white moves by King, it'll be punished by moving Queen to a1 taking Bishop on b2 and immediately checkmating the King.
This diagram shows legal moves for black Knight on c4. Red circles in green ones are marking the squares to which Knight can move either with or without capture. This piece can simply move to b6, d6, e5, e3 and d2. Field b2 isn't available because it's occupied, even by non-friendly Bishop. Also this knight can move a3 or a5 with or without capturing white Rook on b4 (but friendly Bishop on a4 is safe). This position is win in 2 if knight moves a3 (taking the Rook or not doing so) because it can't be taken by white Bishop, which by the way occupies the only square where white King could find his shelter. This is hidden threat, but it's fatal for white (anyway its King will get captured on the next turn even if white moves and checks the black King. White King cannot move into covered b1 and not pleased to move into attacked (by dissolving) a2).
So initiative still decides who wins;)
Notes
This is playable on Game Courier (uncoded).
This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.
By Lev Grigoriev.
Last revised by Lev Grigoriev.
Web page created: 2022-07-25. Web page last updated: 2024-03-16