Ruy Lopez, Exchange Variation Qf6 7.Qd3. There are two "ECO" classifications for the Exchange Variation. Bibliography Ruy Lopez, Exchange Variation The Exchange Variation of the Ruy Lopez is a chess opening that begins with the moves: Black may recapture on c6 with either pawn; although 4...bxc6 is playable, 4...dxc6 is almost always chosen at master level. Black has gained the at the cost of a weakened pawn structure, due to his doubled pawns on c6 and c7. White aims to reach an endgame in which he has the superior pawn structure, which may become an important factor. Thus, Black is compelled to strive for
Tactical wargame on the then-ongoing Cold War, called "Red Star/White Star: Tactical Combat in Western Europe in the 1970s". While the game was successful, Dunnigan was disappointed with it, citing difficulties in realistically portraying tactical combat in a tabletop board game. Dunnigan tried to take tactical games into a new direction in 1973 with "KampfPanzer" and "Desert War", which featured simultaneous movement, expanding on an optional rule for PanzerBlitz. Unfortunately, the quest for greater realism was having a price in complexity and "bookkeeping", or recording of moves on paper. Nonetheless, other tactical games on a man to man level were released with