I would like to know the reason behind the very weakening move g4 recommended by Stockfish in this position:

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2 Answers 2


Well, I am amazed. I thought that it would be another case of a free online engine just not being that strong, but my Stockfish, and Deep Rybka, both like g4 there.

I know I would never have played that move in a million years since the eval is very close to other more normal moves like Re1, but here is what it sees.

It thinks that you can get in g5 when h5 is forced since hg loses by force, and you cannot allow gh there. After h5, that pawn becomes weak and will be lost. As you force in even just a few moves the computer thinks is best, the eval continues to grow, and it leads to a won position almost by force.

There are, of course, many other tries, but they also lead nowhere for black.

  [FEN ""]

  1. d4 h6 2. c4 e6 3. e4 Bb4+ 4. Nc3 Ne7 5. Nf3 Ng6 6. Bd3 O-O 7. O-O Bxc3 8. bxc3 b6 9. g4 c5 10. g5 h5 (10... hxg5 11. Nxg5 $18) 11. Ne1 d5 (11... h4 $2 12. f4 $18) 12. cxd5 exd5 13. Qxh5 $18 Nc6 14. f4 {and you can see that black is lost.}
  • 3
    Agreed, it's very difficult to find g4 imo. But the more I look at it, the more it makes sense to me from a strategic point of view. Black is behind in development, and white has a space advantage in the center as well, so white can (and probably should) just go for the throat here, denying black the chance to catch up.
    – Scounged
    Nov 29, 2019 at 20:28
  • Curious, why do you still have Deep Rybka? That engine's old and been superseded by others. Among conventional engines there's Houdini and Komodo, and if you're looking for free options only there's still Ethereal, Xiphos, Laser, and many others that are both free and stronger.
    – Allure
    Dec 1, 2019 at 20:59
  • I just had it from the old days, and thought I would check it too. It is not like it is super weak. Just a quick second opinion. Dec 1, 2019 at 21:02
  • It's hundreds of elo weaker than the other engines I mentioned though. If you don't have the hardware to run the NN engines, and don't want to pay for Houdini or Komodo, I'd recommend Ethereal, which is both free & open source.
    – Allure
    Dec 1, 2019 at 21:27

White has a wealth of factors working to his advantage:

  • A lead in development.
  • A massive centre.
  • Having control over the dark squares.

These factors allow him to get away with pushing g4. Sure, it weakens the f4- and h4-squares, but his dark-squared bishop can defend them (and Black lacks a dark-squared bishop of his own). There's also the fact that the h6-pawn acts as a hook. If the game continues g5 hxg5 Bxg5, both sides' kingsides have been opened a bit. Then, White could use the g-file with Kh1-Rg1, and suddenly Black's king is actually in more danger than White's.

When one side has a number of advantages, there often comes a moment like this one where he can "cash in" and gain concrete results for it. What's the point of having a number of strategic advantages if they're never eventually used in an offensive manner?

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