Check out Atomic Chess, our featured variant for November, 2024.

This page is written by the game's inventor, Lev Grigoriev. This game is a favorite of its inventor.

Fluidity Chess

Inspiration has come in 2021. I've created this game for Lichess (free libre chess site with millions of players where I started playing chess more seriously), but its developers don't embed new variants (currently), so I've written it here. It hadn't Pawns and rangers' restrictions and was very fast game. 
Then I realized (with editors' help) that game is quite solved, and remastered it in summer of 2023.

The main source of inspiration is Atomic Chess, which is playable on that site. I play it well btw.

Setup

Standard chessboard and setup.

Pieces

It's illegal to move to an occupied square. However, pieces deliver check (attack foe King) as they do in chess, but only on their move destinations. Most of them capture by cutting through the opposite pieces on their way to a free square behind them. So pieces can jump, but only to take; it's possible to capture many pieces at once even if they were in row.

Pawn

Bishop

Knight

Rook

Queen

Bishop + Rook, she is ranger and can capture up to 3 pieces (which aren't in a 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 cut 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:

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 keep him safe.

Rules

Your aim is to checkmate the opposite King. However, stalemate is a loss of player without legal moves (and thus it's another way to win). You also can capture him by cutting through if: 

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:

2 kings and 1 knight endgame is not draw.

Examples

Let us think that all pawns are traded.

diagram

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 2 for White (because King can't take and will have to go to h5/h3, and Rook from d1 can come [back;)] to h1 and checkmate).

diagram

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 the 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 situation unclear: initiative goes to black (Knight can take the b4 Rook by going to a3 with hidden threat to white King which should move to b2 to save the game), but this 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 the Rook on d1 (also possibly capturing Queen by landing behind her) or by King.

diagram

But if white does so or it's black's turn, this is won game for black. If white moves the King, it'll be punished by the Queen moving to now free a1 (and taking Bishop on b2) with immediate checkmate. 
This diagram shows legal moves for black Knight on c4. Red circles in green ones are marking the squares to which the Knight can move either with or without capture. It 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 the Knight moves to 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 the King could find his shelter. This threat is hidden but 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 isn't pleased to move into threatened a2).

So initiative still decides who wins;)

Notes

Knight now worths 4 pawns.

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

Revisions of MSfluiditychess