The King's Gambit is rare in modern high-level play. Revealing the prank, Rajlich admitted that current computer technology is nowhere near solving such a task. In 2012, an April Fools' Day prank by Chessbase in association with Vasik Rajlich-inventor of chess engine Rybka-claimed to have proven to a 99.99999999% certainty that the King's Gambit is at best a draw for White, but only after 3.Be2. Spassky did beat many strong players with it, however, including Bobby Fischer, Zsuzsa Polgar, and a famous brilliancy against Bronstein himself. He inspired Boris Spassky to also take up the King's Gambit, although Spassky was not willing to risk using the opening in any of his World Championship matches. After World War II, 1.e4 openings became more popular again, with David Bronstein being the first grandmaster in decades to use the King's Gambit in serious play.

By the 1920s, 1.e4 openings declined in popularity with the rise of the hypermodern school, with many players switching to 1.d4 and 1.c4 openings and positional play.

While the King's Gambit Accepted was a staple of Romantic era chess, the opening began to decline with the development of opening theory and improvements in defensive technique in the late 19th century. Since 1.e5 does not look like a blunder, White should therefore not be launching an attack. Steinitz had argued that an attack is only justified when a player has an advantage, and an advantage is only obtainable after the opponent makes a mistake. FM Graham Burgess, in his book The Mammoth Book of Chess, noted the discrepancy between the King's Gambit and Wilhelm Steinitz's accumulation theory. It loses by force' and offered his Fischer Defense (3.d6) as a refutation. François-André Danican Philidor (1726–1795), the greatest player and theorist of his day, wrote that the King's Gambit should end in a draw with best play by both sides, stating that 'a gambit equally well attacked and defended is never a decisive, either on one side or the other.' Writing over 150 years later, Siegbert Tarrasch, one of the world's strongest players in the late 19th and early 20th centuries, pronounced the opening 'a decisive mistake' and wrote that 'it is almost madness to play the King's Gambit.' Similarly, future world champion Bobby Fischer wrote a famous article, 'A Bust to the King's Gambit', in which he stated, 'In my opinion the King's Gambit is busted. Nevertheless, players have held widely divergent views on it. The King's Gambit was one of the most popular openings for over 300 years, and has been played by many of the strongest players in many of the greatest brilliancies, including the Immortal Game. It is infrequently seen at master level today, as Black has several methods to obtain equality, but is still popular at amateur level. The King's Gambit was one of the most popular openings until the late 19th century, when improvements in defensive technique led to its decline in popularity. It was examined by the 17th-century Italian chess player Giulio Cesare Polerio.

The King's Gambit is one of the oldest documented openings, appearing in one of the earliest chess books, Luis Ramírez de Lucena's Repetición de Amores y Arte de Ajedrez (1497). Be7–h4+), which may force White to give up castling rights. A downside to the King's Gambit is that it weakens White's king's position, exposing it to the latent threat of. If Black accepts the gambit, White may play d4 and Bxf4, regaining the gambit pawn with central domination, or direct their forces against the weak square f7 with moves such as Nf3, Bc4, 0-0, and g3. White offers a pawn to divert the black e-pawn. The King's Gambit is a chess opening that begins with the moves:

Vienna game falkbeer defence