13 February 2023

Chessify's Other Engines

Continuing with Chessify Progress Report (January 2023), the site mentions four other engines after stalwarts Stockfish and LCZero: Asmfish, Berserk, Koivisto, Sugar AI (and Sugar AI ICCF). I asked the TCEC and CCC '!commands' to tell me more about these engines.


  • !asmfish • asmFish, a port of Stockfish in x86-64 assembly by Mohammed Li, optional using AVX2 and BMI2 instructions, assembled with FASM to run under Windows or UNIX/Linux, first released in June 2016. See also
    https://www.chessprogramming.org/AsmFish and
  • !berserk • Berserk is a UCI-compatible chess engine by Jay Honnold (Zombywafflez), written in C. Initially 2020 a Java project, first release in Feb 2021 under GPL v3.0. First TCEC appearance S21 QL. See
  • !koivisto • Koivisto is a UCI-compatible open source chess engine by Kim K√•hre and Finn Eggers, written in C++. It was first released in September 2020 under GPL v3.0. First TCEC appearance S20 QL. See
    koivisto-chess.com and
  • Sugar • %


  • !asmfish • stockfish ported to assembly ... it's insanely fast!
  • Berserk • %
  • Koivisto • %
  • Sugar • %

Explaining things is not the CCC's strong point. Since Sugar struck out in both !command searches, I went a little deeper. SugaR ICCF chess engine has been added to Chessify (chessify.me; undated).

Not too long ago, Berserk generated some buzz in the engine community. On this blog's series of engine status posts I found the first significant reference in TCEC S22 L3 and CCC16 Blitz Final Both Underway (February 2022). Specifically:-

Since the previous report, '[TCEC] S22 Underway', both QL and L4 have finished and L3 is underway. Young 'Berserk', which finished 9th-10th in S21 QL, won S22 QL and L4 and is currently third among 12 engines in L3.

I decided to give Berserk a try, hoping for results that counter Stockfish's annoying tendency to evaluate many unbalanced positions as 0.00. After the 'Chessify Progress' post, the site opened a Discord server Welcome to the Official Chessify discord! (discord.com). One recent conversation went:-

2023-02-06: GenieGP: ASMFish hasn't existed for a few years now and I was wondering why it was still part of the site? As for SugaR, its development was stopped a year ago, so recently. ShashChess (another Stockfish derivative) could replace it, right? These are my ideas and thanks to you. • tavetius: We can consider adding ShashChess, but we can't remove SugaR and ASMFish, because we have users who use them??

The Discord server is a good source of whys and wherefores concerning the Chessify features. I'll try to keep an eye on it.


Later: A week or so after I posted this, Chessify added a fifth engine: RubiChess. Using the '!commands' again, here is some further info.


  • !rubichess • RubiChess started in 2016 as a C++ hobby project by Andreas Matthies (rubichess). First TCEC appearance S15. See


  • !rubinnue • [i.e. Rubi NNUE]

The CCC link is worth a read: RubiChess NNUE player implemented (talkchess.com; September 2020) And the engine is worth a try.

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