Answers.Body: <p>Obviously, you are not the first chess player to think about alternatives to the 'book moves'.</p>
  
  <p>I think it is a solid assumption that all possible moves that deviate from the book move have been considered by someone already, and probably by someone with some playing strength.<br>
  So either those moves are good enough (equivalent) to 'book moves' and therefore they would have made it in the books by now, or they are (considered) at least slightly inferior.</p>
  
  <p>If you consider playing an inferior move, you will have to balance the expected 'loss' from the inferiority against the potential 'gain' from forcing your opponent into a non-book variant (which <em>you</em> have analyzed in depth before, and he probably didn't). Depending on his strength in 'book openings' compared to his strength in 'think-yourself', this might be a good deal for you or not.</p>
  
  <p>Note that this is not an uncommon idea - nearly all chess players I know have taken this approach from time to time, and more or less successful. Try it, but don't expect your opponent to be shocked out of his mind.</p>
  
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Answers.UserDisplayName: Aganju
Answers.Body: <p>No, not because there are not things that are not sound, but virtually every early divergence, if at all good, has been played...and virtually every bad divergence.</p>
  
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Answers.Text: A century ago, players said that chess was dead and the openings were completely solved, then came the hypermodernists.  This trend continued until, at least, 2000.  Just when chess became stale again, Leela show that you can play the obviously bad 1.a4.
Answers.UserDisplayName: Mike Jones
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Answers.Text: There is a big difference between chess being dead, and virtually all reasonable moves in the very opening having been tried. I am also not talking about some novelty on move 27, just the first 5-10 moves. Try looking at the openings in ChessBase...9 million games covers a lot of early moves.
Answers.UserDisplayName: PhishMaster
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Answers.Text: The example I gave was on move one.  The point is that that move was considered bad and now is considered good.  Your entire counterpoint is invalid just as the changing opening theory.
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Answers.UserDisplayName: PhishMaster
Answers.Body: <p>Depends what you mean by sound.  And what book you think is the authority.</p>
  
  <p>Could a computer beat that move?  Maybe.</p>
  
  <p>Would a person beat it? Much less likely.  </p>
  
  <p>There are many playable moves that are not in the book.  I found an absolutely sound one that is not in the book and always gives some advantage.  I also found an excellent one for time limited OTB play that gives a good winning percentage. </p>
  
  <p>Eventually every good move will be played and should end up in the book.</p>
  
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Answers.UserDisplayName: yobamamama
Body: <p>In the opening stage, are there any moves that are perfectly sound but are not book moves? Here a book move, is defined in Wikipedia as follows: </p>
  
  <blockquote>
    <p>Opening moves that are considered standard (often catalogued in a reference work such as the Encyclopaedia of Chess Openings) are referred to as "book moves", or simply "book". Reference works often present move sequences in simple algebraic notation, opening trees, or theory tables.</p>
  </blockquote>
  
  <p>By a sound move, I mean a move that is completely reasonable in a certain opening position and does not create any weaknesses. (There may be a better definition, but you probably know what I mean.)</p>
  
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Comments.CreationDate: 2019-12-10T16:53:52.860Z
Comments.Text: Have a look at the [irregular openings](https://en.wikipedia.org/wiki/Irregular_chess_opening): Depending the *opening book* you choose as a frame of reference for what is recognized as *regular*, you might find those mentioned on the linked page as good candidates for what you're looking for, e.g. `1.b3`.
Comments.UserDisplayName: Ellie
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Comments.Text: If both sides make lesser popular moves (though sound), they can be out of the book very quickly. For example, `1.d4 d5 2.Nf3 Bg4 3.g3 e6 4.Ne5`, `4.Ne5` is not in lichess master game database.
Comments.UserDisplayName: Akavall
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Comments.Text: 'Book' is an arbitrary definition. There are definitely enough sound moves for not all of them to be labeled 'book'.
Comments.UserDisplayName: Alexander Geldhof
Tags: <opening><theory>
Title: Are there any moves in the opening stage that are perfectly sound but not book moves?
ThreadText: # Are there any moves in the opening stage that are perfectly sound but not book moves?
  
  (Asked by: username_0 on 2019-12-10)
  
  In the opening stage, are there any moves that are perfectly sound but are not book moves? Here a book move, is defined in Wikipedia as follows:
  
  > Opening moves that are considered standard (often catalogued in a reference work such as the Encyclopaedia of Chess Openings) are referred to as "book moves", or simply "book". Reference works often present move sequences in simple algebraic notation, opening trees, or theory tables.
  
  By a sound move, I mean a move that is completely reasonable in a certain opening position and does not create any weaknesses. (There may be a better definition, but you probably know what I mean.)
  
  **Tags:** opening, theory
  
  > **Comments:**
  > **username_1**: Have a look at the [irregular openings](https://en.wikipedia.org/wiki/Irregular_chess_opening): Depending the *opening book* you choose as a frame of reference for what is recognized as *regular*, you might find those mentioned on the linked page as good candidates for what you're looking for, e.g. `1.b3`.  
  > **username_2**: If both sides make lesser popular moves (though sound), they can be out of the book very quickly. For example, `1.d4 d5 2.Nf3 Bg4 3.g3 e6 4.Ne5`, `4.Ne5` is not in lichess master game database.  
  > **username_3**: 'Book' is an arbitrary definition. There are definitely enough sound moves for not all of them to be labeled 'book'.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_4 on 2019-12-10. Score: 1
  
  Obviously, you are not the first chess player to think about alternatives to the 'book moves'.
  
  I think it is a solid assumption that all possible moves that deviate from the book move have been considered by someone already, and probably by someone with some playing strength.  
  So either those moves are good enough (equivalent) to 'book moves' and therefore they would have made it in the books by now, or they are (considered) at least slightly inferior.
  
  If you consider playing an inferior move, you will have to balance the expected 'loss' from the inferiority against the potential 'gain' from forcing your opponent into a non-book variant (which *you* have analyzed in depth before, and he probably didn't). Depending on his strength in 'book openings' compared to his strength in 'think-yourself', this might be a good deal for you or not.
  
  Note that this is not an uncommon idea - nearly all chess players I know have taken this approach from time to time, and more or less successful. Try it, but don't expect your opponent to be shocked out of his mind.
  
  
  ---
  
  ### Answer by username_5 on 2019-12-10. Score: -1
  
  No, not because there are not things that are not sound, but virtually every early divergence, if at all good, has been played...and virtually every bad divergence.
  
  > **Comments:**
  > **username_6**: A century ago, players said that chess was dead and the openings were completely solved, then came the hypermodernists.  This trend continued until, at least, 2000.  Just when chess became stale again, Leela show that you can play the obviously bad 1.a4.  
  > **username_5**: There is a big difference between chess being dead, and virtually all reasonable moves in the very opening having been tried. I am also not talking about some novelty on move 27, just the first 5-10 moves. Try looking at the openings in ChessBase...9 million games covers a lot of early moves.  
  > **username_6**: The example I gave was on move one.  The point is that that move was considered bad and now is considered good.  Your entire counterpoint is invalid just as the changing opening theory.  
  
  ---
  
  ### Answer by username_7 on 2019-12-10. Score: -1
  
  Depends what you mean by sound. And what book you think is the authority.
  
  Could a computer beat that move? Maybe.
  
  Would a person beat it? Much less likely.
  
  There are many playable moves that are not in the book. I found an absolutely sound one that is not in the book and always gives some advantage. I also found an excellent one for time limited OTB play that gives a good winning percentage.
  
  Eventually every good move will be played and should end up in the book.
  
  
  ---
  
  