| 1 | p.boxed |
| 2 | | Move twice at every turn. The goal is to capture the king. |
| 3 | |
| 4 | p. |
| 5 | The only difference with orthodox chess is the double-move rule, |
| 6 | but this affects the game a lot. |
| 7 | |
| 8 | p. |
| 9 | At the very first move of the game, white make only one move - as usual. |
| 10 | However, after that and for all the game each side must play twice at |
| 11 | every turn (even if the first move captures the enemy king). |
| 12 | |
| 13 | figure.diagram-container |
| 14 | .diagram.diag12 |
| 15 | | fen:rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR: |
| 16 | .diagram.diag22 |
| 17 | | fen:r1bqkbnr/pppp1ppp/2n5/4p3/2B1P3/5Q2/PPPP1PPP/RNB1K1NR: |
| 18 | figcaption. |
| 19 | Left: after the moves 1.e4 e5, the 'd' pawn is pinned. |
| 20 | Right: the black king is "under check". |
| 21 | |
| 22 | p. |
| 23 | In the diagram position on the left, after the first black move ...e5, |
| 24 | moving the 'd' pawn would allow 2.Bb5,Bxe8 capturing the king. |
| 25 | On the right, after 2.Qf3,Bc4 the threats are 3.Bxf7,Bxe8 and 3.Qxf7,Qxe8. |
| 26 | |
| 27 | h3 En-passant capture |
| 28 | |
| 29 | p. |
| 30 | Capturing en-passant is allowed under certain conditions. |
| 31 | If the opponent moved a pawn allowing such a capture (once or twice), |
| 32 | then (to take it) you must capture en-passant at the first move of your turn. |
| 33 | After that, if (and only if) there is another en-passant capture available |
| 34 | you can play it on the second move. |
| 35 | |
| 36 | p. |
| 37 | Note: if a pawn 2-squares jump was made and then a piece landed at the |
| 38 | en-passant square at the second move, a pawn capture on this square |
| 39 | takes only the piece. |
| 40 | And, if a pawn advanced twice then en-passant capture |
| 41 | on its first movement is impossible (the pawn is now "too far"). |
| 42 | |
| 43 | h3 More information |
| 44 | |
| 45 | p |
| 46 | | This variant is derived from |
| 47 | a(href="/variants/Doublemove1") Marseillais chess |
| 48 | | . It is also playable |
| 49 | a(href="https://greenchess.net/rules.php?v=double-move") on greenchess |
| 50 | | . |
| 51 | |
| 52 | p Inventor: Fred Galvin (1957) |