What is "open game"

n. (alternative case form of Open Game English)

An Open Game (or Double King's Pawn Opening) is a chess opening which begins with the following moves:

White has moved the king's pawn forward two squares and Black replies in kind, the result being an Open Game. Other responses to 1.e4 are termed Semi-Open Games, or Single King's Pawn Games.

The term Open Game can also refer to any chess position where ranks, files and diagonals are open, and usually favor tactical gameplay. Bishops are generally stronger than knights on an open board due to their ability to cover longer distances.