Top Chess Engine Championship


Top Chess Engine Championship, formerly known as Thoresen Chess Engines Competition, is a computer chess tournament that has been run since 2010. It was organized, directed, and hosted by Martin Thoresen until the end of Season 6; from Season 7 onward it has been organized by Chessdom. It is often regarded as the Unofficial World Computer Chess Championship because of its strong participant line-up and long time-control matches on high-end hardware, giving rise to very high-class chess. The tournament has attracted nearly all the top engines compared to the World Computer Chess Championship.
After a short break in 2012, TCEC was restarted in early 2013 and is currently active with 24/7 live broadcasts of chess matches on its website.
Since season 5, TCEC has been sponsored by Chessdom Arena.

Overview

Basic structure of competition

The TCEC competition is divided into seasons, where each season happens over a course of a few months, with matches played round-the-clock and broadcast live over the internet. Each season is divided into several tournaments: a Leagues Season, a Cup, a Swiss tournament, a Fischer Random Chess tournament. Additionally, seasons contain various bonus contests, like the 'Viewer Submitted Opening Bonus'.
Prior to season 21, there was originally one tournament in each season. This tournament consisted of several qualifying stages and one "superfinal", and the winner of the superfinal is called the "TCEC Grand Champion" until the next season. Prior to season 11, the tournament used a cup format, while starting in Season 11, the tournament used a division system. Starting in season 13, there was also a cup tournament consisting of the top 32 engines in the main tournament, resulting in a 5-round single elimination tournament.

Engine settings/characteristics

is set to off. All engines run on Linux on the same hardware and use the same opening book, which is set by the organizers and changed in every stage. Large pages are enabled, and access to endgame tablebases including Syzygy 7-men is permitted. Engines are allowed updates between stages; if there is a critical play-limiting bug, they are also allowed to be updated once during the stage. In previous seasons, if an engine crashes 3 times in one event, it is disqualified to avoid distorting the results for the other engines; however, starting in TCEC Season 20, an engine is allowed to crash any number of times without being disqualified from the current event, although the engine will still be disqualified from future events unless the crash is fixed. TCEC generates an Elo rating list from the matches played during the tournament. An initial rating is given to any new participant based on its rating in other chess engine rating lists.

Criteria for entering the competition

There is no definite criterion for entering into the competition, other than inviting the top participants under active development from various rating lists which can run on their Linux platform. Originally, TCEC used Windows instead of Linux. In addition, either XBoard or UCI protocol are required to participate.
Usually chess engines that support multiprocessor mode are preferred, and engines in active development are given preference. Since TCEC 12, engines like LCZero which use GPUs for neural processing were supported.
Initially, the list of participants was personally chosen by Thoresen before the start of a season. His stated goal was to include "every major engine that is not a direct clone". In TCEC 13, DeusX was banned due to being a clone of Leela, and in TCEC 20, Houdini, Fire, Rybka, and Critter were banned due to allegations of plagiarism.

Tournament results

The number within the brackets denote the number of times the engine has won the particular competition.

TCEC Seasons

TCEC Cups

TCEC Swiss

TournamentDateWinnerRunner-up
TCEC Swiss 1Apr 2021KomodoDragon Stockfish
TCEC Swiss 2Nov – Dec 2021KomodoDragon Stockfish
TCEC Swiss 3May – Jul 2022Stockfish LCZero
TCEC Swiss 4Jan – Feb 2023Stockfish LCZero, KomodoDragon
TCEC Swiss 5Jun - Jul 2023Stockfish LCZero
TCEC Swiss 6Jan – Feb 2024LCZero Stockfish
TCEC Swiss 7Sep 2024LCZero Stockfish
TCEC Swiss 8Apr - Jun 2025Stockfish LCZero
TCEC Swiss 9Nov - Dec 2025Stockfish LCZero

TCEC FRC (Fischer Random Chess)

Replaced by TCEC FRD.
TournamentDateWinnerFinal/Superfinal scoreRunner-up
TCEC FRC 1Oct – Nov 2019Stockfish + 10 = 10 - 0AllieStein
TCEC FRC 2Nov 2020Stockfish + 8 = 42 - 0LCZero
TCEC FRC 3Mar 2021KomodoDragon + 2 = 47 - 1Stockfish
TCEC FRC 4Dec 2021 – Jan 2022Stockfish + 13 = 28 - 9LCZero
TCEC FRC 5Jul 2022Stockfish + 17 = 20 - 13LCZero
TCEC FRC 6May 2023Stockfish + 15 = 23 - 12LCZero

TCEC DFRC (double Fischer Random Chess)

Replaced by TCEC FRD. In DFRC, the start positions of the pieces are randomized independently for both players.
TournamentDateWinnerFinal scoreRunner-up
TCEC DFRC 1Jul – Aug 2022Stockfish + 18 = 23 - 9LCZero
TCEC DFRC 2May - Jun 2023Stockfish + 10 = 33 - 7LCZero

TCEC FRD (Fischer Random Double)

In FRD, which has superseded both FRC and DFRC, the qualifying rounds are played in the Fischer Random System and the finals in the double Fischer Random System.
TournamentDateWinnerFinal scoreRunner-up
TCEC FRD 1Nov - Dec 2023Stockfish + 11 = 29 - 10LCZero
TCEC FRD 2Jun - Jul 2024Stockfish + 20 = 16 - 14LCZero
TCEC FRD 3Feb 2025Stockfish + 13 = 25 - 12LCZero
TCEC FRD 4Sep - Oct 2025Stockfish + 18 = 18 - 14LCZero

TCEC 4k

Engines are limited to in program size.
TournamentDateWinnerFinal scoreRunner-up
TCEC 4kIDec 2022ice4 45.5/48 4ku
TCEC 4kIIMay 2023ice4 + 5 = 15 - 44ku
TCEC 4kIIIDec 2023 – Jan 20244ku + 13 = 30 - 7ice4
TCEC 4kIVAug 2024ice4 + 29 = 20 - 14ku
TCEC 4kVApr 2025ice4 + 29 = 20 - 14ku

Other TCEC tournaments