h3 Basics
p.
- TODO: explain, every turn twice except if check on 1st turn, or
- very first move in game.
- En-passant: possible in any order if 2 ep squares,
- otherwise has to be the first move.
- OK even if opponent moved his pawn at subturn 1.
+ At the very first move of the game, white make only one move - as usual.
+ However, after that and for all the game each side must play twice at
+ every turn. There are two exceptions:
+
+ul
+ li.
+ If the first move gives check (maybe checkmate),
+ then a second move isn't played.
+ li.
+ If no move is available after the first move, then it's stalemate
+ and again, there is no second move.
p.
- PGN game notation: since there are two moves at each turn except on move 1,
- a double move in the game is indicated as two comma-separated (ordered) moves,
- as in 3.Na5,Bd3 e6,f4 (the two first are white moves,
+ About the PGN game notation: when a side plays two moves in a row,
+ they are separated (in order) by a comma in the PGN.
+ Example: 3.Na5,Bd3 e6,f4 (the two first are white moves,
the two others are black moves).
figure.diagram-container
| fen:r1bqkbnr/pppp1p1p/2n5/4p2p/4P3/5N2/PPPP1PPP/RNB1KB1R:
figcaption After the moves 1.e4 e5,Nc6 2.Qh5,Nf3 g6,gxh5
+h3 En-passant capture
+
+p.
+ Capturing en-passant is allowed under certain conditions.
+ If the opponent moved a pawn allowing such a capture (once or twice),
+ then (to take it) you must capture en-passant at the first move of your turn.
+ After that, if (and only if) there is another en-passant capture available
+ you can play it on the second move.
+
+p.
+ Note: if a pawn 2-squares jump was made and then a piece landed at the
+ en-passant square at the second move, a pawn capture on this square
+ takes only the piece.
+ And, if a pawn advanced twice then en-passant capture
+ on its first movement is impossible (the pawn is now "too far").
+
h3 More information
p