Atomic chess

What this variant is

Atomic chess is standard chess with one violent addition. Pieces move exactly as they always do, from the usual starting array, and castling, capture in passing and promotion are unchanged. What changes is what a capture does.

Explosions

When any capture is made, an explosion goes off on the square where the capture happened. It destroys three things at once.

• The piece that was captured.
• The piece that did the capturing, which is removed along with its victim.
• Every piece other than a pawn standing on any of the eight squares that touch the square of the capture, whichever side it belongs to.

Pawns are the exception. A pawn on a neighbouring square is not harmed by the blast. A pawn that is itself the captured man is removed, of course, and a pawn that does the capturing is removed like any other capturer. So pawns are shielded from other people’s explosions but not from their own.

A capture in passing explodes on the square the capturing pawn moves to, which is not the square the captured pawn was standing on. The captured pawn is still removed.

A move that is not a capture does nothing unusual. Only captures explode.

What happens to kings

• A king may never capture. It moves one square as usual, but only onto an empty square, because a king capture would blow the king up.
• A capture that would destroy your own king, because the king stands next to the square of the explosion, is illegal. You cannot play it, even to save the game.
• A capture that destroys the enemy king ends the game immediately in your favour. This overrides everything, including any check against you at the time.
• Two kings standing on neighbouring squares are never in check from each other, and neither can be checked by anything while they are adjacent. Walking your king up against the enemy king is a real defensive resource.

Ordinary check still exists, and you must still answer it. But because a king can be destroyed as well as mated, the practical winning method is almost always an explosion beside the enemy king rather than a checkmate.

Winning

• Destroying the enemy king in an explosion. The game ends at once.
• Checkmate in the ordinary sense, which is rare but possible.
• Resignation, or the opponent running out of time.

Drawing

Stalemate is a draw, and so are agreement, threefold repetition and the fifty-move rule, which are applied automatically for both sides. Positions where nothing can be forced do occur, particularly when both sides are down to pawns that can never make contact.

How it changes your play

• Keep your king away from your own pieces. A king surrounded by its own defenders is a target, because any capture among them takes the king with it.
• Pawns are the best shields in the game, since they survive nearby explosions. A pawn wall around the king is far more useful than a piece wall.
• Do not take a piece just because you can. Ask what else is standing within one square of it, on both sides.
• Getting a knight near the enemy king is worth more than a queen, because a knight can threaten to capture something adjacent to it.