Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A Semi-Closed Game (or Semi-Closed Opening) is a chess opening in which White opens with the queen's pawn 1.d4 but Black does not make the symmetrical reply 1...d5. (The openings starting 1.d4 d5 are the Closed Games.)By far the most important category of the semi-closed openings are the Indian systems, which begin 1.d4 Nf6. As these defenses have much in common and have a great deal more theory than all the remaining semi-closed openings put together, they are treated in a separate article; see Indian defense for details.