Irregular chess opening

This article uses algebraic notation to describe chess moves.

In chess, an irregular opening is an opening considered unusual or unorthodox. In the early 19th century the term was used for any opening not beginning with 1.e4 e5 (the Open Game) or 1.d4 d5 (the Closed Game). As opening theory has developed and openings formerly considered "irregular" have become standard, the term has been used less frequently.^[1]

Because these openings are not popular with chess players, the standard opening references such as Modern Chess Openings (MCO) and Encyclopaedia of Chess Openings (ECO) do not cover them in detail.

^ Hooper & Whyld, The Oxford Companion to Chess, Oxford University Press, 1996, p 182, "Irregular opening, in the early 19th century any opening that did not begin with 1.e4 e5 or 1.d4 d5. However, Jaenisch said, 'As this distinction is purely arbitrary, and unfounded on principle, we cannot ourselves adopt it. We distinguish all the openings as "correct", or else as "incorrect" or "hazardous".' Since then many so-called irregular openings have become standard play. These and many other openings have acquired names and the term irregular opening has gradually fallen into disuse."

[Oxford-1] Hooper & Whyld, The Oxford Companion to Chess, Oxford University Press, 1996, p 182, "Irregular opening, in the early 19th century any opening that did not begin with 1.e4 e5 or 1.d4 d5. However, Jaenisch said, 'As this distinction is purely arbitrary, and unfounded on principle, we cannot ourselves adopt it. We distinguish all the openings as "correct", or else as "incorrect" or "hazardous".' Since then many so-called irregular openings have become standard play. These and many other openings have acquired names and the term irregular opening has gradually fallen into disuse."

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