How to Play SwapChess

Everything from standard chess still applies. One extra rule changes all of it.

SwapChess is ordinary chess with a single addition called the SwapMove. If you already know how the pieces move, you know 95% of this game. The remaining 5% is what makes your pawns worth far more than one point each — and what makes a bad position recoverable in a way it never is in classical chess.

This page covers the SwapMove in full: the exact legality conditions, how it interacts with check, promotion, castling and the draw rules, and a set of worked examples.

The SwapMove in one sentence

On your turn, instead of making a normal move, you may remove one of your own pawns from the board and teleport any one of your other pieces onto the square that pawn was standing on.

Read that carefully, because two details trip up almost everyone at first:

• It is not a swap of positions. The name is a slight lie. The pawn does not move to where your piece was. The pawn is gone — captured, removed, off the board — and your piece takes its place. The square your piece came from is left empty.
• It costs your entire turn. A SwapMove is your move. You do not also get to move a piece normally.

So every SwapMove is a real sacrifice. You are paying a pawn for a teleport.

Legality conditions

A SwapMove is legal if and only if all of the following hold:

Notice what is not on that list. There is no distance limit, no line-of-sight requirement, and no restriction on what is in between. A knight on b1 can teleport to a pawn on h7 in a single move. Blocked positions do not block a SwapMove.

Interaction with the standard rules

Check and checkmate

A SwapMove is a legal escape from check if it resolves the check — by blocking the checking line, by moving the king to safety, or by placing a piece where it interposes. Conversely, a SwapMove can deliver check and can deliver checkmate. Teleporting a queen next to a cornered king is a perfectly ordinary way to end a game here.

Because swaps ignore blockers, "my king is safe, nothing can reach it" is a much weaker statement in SwapChess than in chess. Anything your opponent owns is one pawn away from any pawn they own.

Promotion

Promotion is unchanged: a pawn that reaches the eighth rank promotes as normal, and you pick the piece. But a SwapMove never promotes anything. A rook that teleports onto a pawn sitting on the seventh rank is still a rook, and it does not promote if it later reaches the eighth by a normal move — only pawns promote.

There is a trap here worth naming: if you swap a piece onto your own advanced passed pawn, you have just destroyed the pawn that was about to become a queen. Check whether the pawn you are spending is the most valuable thing you own.

Castling

Castling rights follow the pieces. If you teleport your king off e1, or a rook off a1 or h1, you lose the ability to castle on that side, exactly as if you had moved them normally.

En passant

A SwapMove clears any en passant opportunity, the same way any non-pawn move does. If your opponent has just played a double pawn push and you respond with a swap, the en passant capture is no longer available to you next turn.

Draws and the move clocks

A SwapMove advances the move counter like any other move. It increments the halfmove clock rather than resetting it, so a long series of swaps still counts toward the 75-move rule. All the standard draw conditions apply: stalemate, insufficient material, the 75-move rule and fivefold repetition.

Worked examples

1. The long-range knight

Your knight sits on b1. Your opponent's king is castled kingside behind pawns on f7, g7 and h7, and you have a pawn on g6 that has been sitting there doing nothing. Swap: the g6 pawn comes off, the knight lands on g6. That knight is now forking whatever sits on e7 and f8, and it took one move to get there instead of four.

Cost: one pawn. Benefit: a knight in the opponent's camp, immediately, with no route to block.

2. Emergency defence

Your king is under pressure and your queenside pieces are hopelessly far away. You have a pawn on f2 in front of your king. Swap your undeveloped a1 rook onto f2 — the rook is now defending the king's immediate neighbourhood, and the attacking lines that ran through f2 now run into a rook.

Note the trade-off: you removed a shelter pawn to place a defender. Sometimes that is a net loss. Count the resulting attackers and defenders before you commit.

3. The bishop that changes colour

Your dark-squared bishop is useless — every target is on a light square. In classical chess you are stuck with it forever. Here, if you have a pawn standing on any light square, one SwapMove puts your bishop on light squares permanently. This is a genuinely unique resource and one of the strongest justifications for spending a pawn.

4. Escaping a bind

Your pieces are cramped behind your own pawn chain and you have no useful moves. Swaps ignore blockers entirely, so a locked position is never truly locked. Spend a pawn from the chain and jump a piece to the other side of it.

Using the interface

1. Click Swap Mode in the sidebar, or press S. On mobile the button sits directly under the board.
2. Squares holding a piece you can legally swap are highlighted in blue.
3. Click the piece you want to teleport. The highlights update to show which of your pawns it may land on.
4. Click the destination pawn. The swap executes immediately.
5. Press Escape at any point to cancel and go back to normal moves.

The status panel tells you how many swaps are currently available to you. If it says zero, the Swap Mode button is disabled — that usually means you have no pawns left, no non-pawn pieces left, or every candidate swap would leave your king in check.

In the move history, swaps are logged as from→to in blue to distinguish them from normal moves, which are recorded in standard coordinate notation.

Playing against the bot

Three difficulty levels are available. Where Stockfish is installed on the server, the bot uses it for its normal moves, with search depth scaled by the difficulty you pick; otherwise it falls back to a heuristic that favours captures.

Either way, the bot will occasionally choose a SwapMove instead of a normal move — roughly one turn in seven when a legal swap exists. It picks among available swaps without deep evaluation, so its swaps are unpredictable rather than precise. Do not assume a bot swap was clever; check what it actually threatens.

Multiplayer

Choose Create Room to generate a six-character code, then send that code to someone. They choose Join Room, enter it, and the game begins. The player who creates the room plays White. Games are held in server memory only and are not saved — closing the tab ends the game.

Your display name is stored in your own browser so you do not have to retype it. Nothing else about your games is retained. See the privacy policy for details.

Once the rules are clear, the interesting question is when a teleport is actually worth a pawn. That is covered in SwapMove strategy.