Complex sentence: The game starts with white and black pawns set as usual, but the initial position of other pieces is selected by the players in the following way: first, White places one of his pieces on his first rank, and then Black does the same.
Split into simpler sentences: The game starts with white and black pawns set as usual, but the initial position of other pieces is selected by the players. White first places one of his pieces on his first rank, and then Black does the same.