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Donald Benge, 1975. White makes five moves, then each side makes ten moves. A unit may move a maximum of once during a sequence, unless its previous move captured / gave check. If you check or capture before your sequence ends, or offers to be captured en passant, the opponent gets one move. Units exposed to capture in this way, or whose moves give check, or pawns which promote, are excused from the prohibition on a second move. When a reply-move gives check, I did not allow the turn-mover to move a piece already moved, even to avoid checkmate.
These are simple illustrations rather than strong opponents.
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