King's Pawn Game

The King's Pawn Game is any chess opening starting with the move:

1. e4

White opens with the most popular of the twenty possible opening moves. Although effective in winning for White (54.25%), it is not as successful as the four next most common openings for White: 1.d4 (55.95%), 1.Nf3 (55.8%), 1.c4 (56.3%), and 1.g3 (55.8%). Since nearly all of these openings have names of their own, the term "King's Pawn Game", unlike Queen's Pawn Game, is rarely used to describe the opening of the game.

Advancing the king's pawn two squares is highly useful because it occupies a center square, attacks the center square d5, and allows the development of White's king's bishop and queen. Chess legend Bobby Fischer said that the King's Pawn Game is "best by test".

King's Pawn Games are further classified by whether Black responds with 1...e5 or not. Openings beginning with 1.e4 e5 are called Double King's Pawn Games (or Openings), Symmetrical King's Pawn Games (or Openings), or Open Games – these terms are equivalent. Openings where Black responds to 1.e4 with a move other than 1...e5 are called Asymmetrical King's Pawn Games or Semi-Open Games.

The Encyclopaedia of Chess Openings classifies all King's Pawn Games into volumes B or C: volume C if the game starts with 1.e4 e6 (the French Defence) or 1.e4 e5; volume B if Black answers 1.e4 with any other move. The rare instances where the opening does not fall into a more specific category than "King's Pawn Game" are included in codes B00 (includes the Nimzowitsch Defence and unusual moves after 1.e4), C20 (includes Alapin's Opening and unusual moves after 1.e4 e5), C40 (includes the Latvian Gambit and unusual moves after 1.e4 e5 2.Nf3), and C50 (includes the Hungarian Defense, the Giuoco Pianissimo, and unusual moves after 1.e4 e5 2.Nf3 Nc6 3.Bc4).