I saw a stream by IM Eric Rosen where he showed a stronger version of stockfish than the one on lichess.org. He said that it is a version that is given to masters with the evaluation function specifically tuned to their playing style.

Does anyone have an idea how this personal tuning is accomplished? I know that stockfish regularly gets tuned, but I believe that is for strength optimization not playing style “fitting”.

  • Could a link to the video be provided? I find a bit odd building personalised versions matching a player's style AND also being stronger than the official release. I find it an interesting idea though: probably it's not that important to lose a few Elo points if you get lines that better fit your style.
    – emdio
    Commented Jan 10, 2021 at 20:25
  • @emdio sorry, I tried looking for it, but had no luck finding it. I think it might've been an old video. Commented Jan 25, 2021 at 18:36

1 Answer 1


There are many elements that a computer looks at to determine how the computer plays. A more defensive computer would place more value on the pawns around the king. A more attacking computer would place more value on retaining pieces, to maintain the attacking possibilities. The choice of opening and the central pawn structure affects the overall playing style.

Galahad chess and Chessmaster had to option to change around two dozen of these evaluation values. Beowulf read these values from a config file, but they weren't easily modified.

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