Shown above are three chess openings which share a common word in their name (two of the openings being the King’s ______ and the Queen’s ______). The common word stems from the fact that these openings were introduced to modern chess by a player from a certain country. Due to the ancient variant of the game he had learnt, the player was accustomed to a certain under-utilization, which is seen in the moves of the black pieces in these openings.
This under-utilization was the only legal move for particular pieces in the variant, and had also been the norm in chess for a very long time. When the rules of chess were changed, a new way of capturing pieces in passing was also added.
What word fills in the blanks? What under-utilization is being talked about? What is this new way of capturing called?