What is Atomic?
Atomic is chess with explosive captures. When a piece captures, both it and the captured piece are removed, together with every piece other than a pawn on the eight squares around the capture, whichever side they belong to. Pawns next to the blast survive.
The aim is to blow up the enemy king: a capture next to it, or on it, wins at once. Checkmate still wins as well. Because a capture also destroys the capturing piece, a king can never capture, and you may not make a capture that would blow up your own king.
The explosions make the game fast and tactical. Kings standing side by side cannot be checked by each other's pieces, since capturing one king would blow up the other, so a king often seeks safety right next to the enemy king.
Rule changes
| Rule | Standard Chess | Atomic |
|---|---|---|
| Captures | Standard ChessThe captured piece is removed and the capturing piece takes its square. | AtomicAn explosion removes the capturing piece, the captured piece and every piece except pawns on the eight surrounding squares. For en passant, the blast is centred on the square the pawn lands on. |
| The king | Standard ChessCaptures like any other piece. | AtomicCan never capture, and you may not make a capture that blows up your own king. |
| Check | Standard ChessA king is in check when an enemy piece attacks it. | AtomicThe same, except that a king touching the enemy king cannot be in check, because taking it would blow up both kings. |
| How to win | Standard ChessCheckmate the opponent's king. | AtomicBlow up the opponent's king with a capture next to it, or checkmate. An explosion that takes the enemy king wins even if your own king is in check. |
| Draws | Standard ChessStalemate, threefold repetition, the fifty-move rule and insufficient material. | AtomicStalemate, threefold repetition and the fifty-move rule. Lack of material draws only when nothing but the kings and at most one knight or bishop is left. |
History
Atomic chess as it is played today took shape on internet chess servers in the 1990s, where it quickly became one of the most played variants.
It has kept that place on modern chess sites, with its own ratings, opening theory and tournaments. Many of its openings aim for a quick explosion next to the enemy king, and strong players have worked out how to defend against them.