Progressive chess is a chess variant in which players, rather than just making one move per turn, play progressively longer series of moves. The game starts with White making one move, then Black makes two consecutive moves, White replies with three, Black makes four and so on. Progressive chess can be combined with other variants; for example, when circe is played as a game, it is usually progressively. Progressive chess is considered particularly apt for playingcorrespondence chess using mail or some other slow medium, because of the relatively small number of moves in a typical game.
Rules
There are two main varieties of progressive chess: Italian progressive chess and Scottish progressive chess. The two have the following rules in common:
A check must be escaped from on the first move of a series—if this cannot be done, it is checkmate and the game is lost.
En passant captures of pawns are allowed if the pawn in question moved two squares in one move, but no further, at some point during the last turn, but the capture must be made on the first move of a series.
If ten consecutive turns are played with no captures and no pawn moves, then the game is declared a draw unless one of the players can force a checkmate.
If at any stage a player has no legal moves but is not in check, the game is a draw by progressive stalemate.
Italian and Scottish progressive chess are distinguished by rules on when a player is allowed to give check:
Scottish progressive chess: check may be given on any move of a series, but a check ends the series—all further moves that would otherwise be allowed are forfeited. This has no effect on the other player's next series—he will receive as many moves as he would have had the other player played his full series.
Italian progressive chess: a check may only be given on the last move of a full series —giving a check at any other point in a series is illegal. In particular, if the only way to escape a check is to give check on the first move of the series, then the game is lost by the player in check by "progressive checkmate".
Progressive chess, like orthodox chess, is notated with algebraic notation. However, the numbering of moves is handled slightly differently. Rather than one White and one Black move being given under each move number, each turn by each player is given its own move number. In this way, the move number is equal to the number of moves in a series available to a player on that turn.
Other variations
There is another form of progressive chess, English progressive chess, which makes quite a significant change to the rules: within each turn, no piece may be moved twice until every other piece which has a legal move has moved once; no piece may move three times until every other piece which can has moved twice; and so on. These restrictions do not carry over from one turn to the next—so the opening 1.e4 2.e6 f6 3.e5 Nf3 Bc4 is legal, but the sequence 1.e4 2.e6 f6 3.e5 Ba6 Bxb7 is not. There is no en passant capture under English rules, and rules on checks follow the Scottish rules. Progressive Take-All uses the same rules as Progressive chess, but involves capturing all pieces of your opponent's instead of checkmate. Pawns can also be promoted to Kings. In Logical progressive chess there's no castling or pawn two advance since these rules were added to speed up the game, which is not relevant in progressive form.
