Top Chess Engine Championship, formerly known as Thoresen Chess Engines Competition (TCEC or nTCEC), 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 (as nTCEC) and is currently active (renamed as TCEC in early 2014) 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
Pondering 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 (8-cores or higher), 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 (engine in Fritz up to TCEC 16), 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 Season Date TCEC Grand Champion Elite match/Superfinal scoreRunner-up TCEC Season 1 Dec 2010 – Feb 2011 Houdini (1) + 12 = 23 - 5 Rybka TCEC Season 2 Feb – Apr 2011 Houdini (2)+ 9 = 26 - 5 Rybka TCEC Season 3 Apr – May 2011 colspan="5" TCEC Season 4 Jan – May 2013 Houdini (3)+ 6 = 38 - 4 Stockfish TCEC Season 5 Aug – Dec 2013 Komodo (1) + 10 = 30 - 8 Stockfish TCEC Season 6 Feb – May 2014 Stockfish (1) + 13 = 45 - 6 Komodo TCEC Season 7 Sep – Dec 2014 Komodo (2) + 7 = 53 - 4 Stockfish TCEC Season 8 Aug – Nov 2015 Komodo (3) + 9 = 89 - 2 Stockfish TCEC Season 9 May – Dec 2016 Stockfish (2) + 17 = 75 - 8 Houdini TCEC Season 10 Oct – Dec 2017 Houdini (4) + 15 = 76 - 9 Komodo TCEC Season 11Jan – Apr 2018Stockfish (3) + 20 = 78 - 2Houdini TCEC Season 12Apr – Jul 2018Stockfish (4) + 29 = 62 - 9Komodo TCEC Season 13Aug – Nov 2018Stockfish (5) + 16 = 78 - 6Komodo TCEC Season 14Nov 2018 – Feb 2019Stockfish (6) + 10 = 81 - 9LCZero TCEC Season 15Mar – May 2019LCZero (1) + 14 = 79 - 7Stockfish TCEC Season 16Jul – Oct 2019Stockfish (7) + 14 = 81 - 5AllieStein TCEC Season 17Jan – Apr 2020LCZero (2) + 17 = 71 - 12Stockfish TCEC Season 18May – Jul 2020Stockfish (8) + 23 = 61 - 16LCZero TCEC Season 19Aug – Oct 2020Stockfish (9) + 18 = 73 - 9LCZero TCEC Season 20Dec 2020 – Feb 2021Stockfish (10) + 14 = 78 - 8LCZero TCEC Leagues Season 21May – Aug 2021Stockfish (11) + 19 = 74 - 7LCZero TCEC Leagues Season 22Jan – Apr 2022Stockfish (12) + 28 = 63 - 9KomodoDragon TCEC Leagues Season 23Aug – Nov 2022Stockfish (13) + 27 = 63 - 10LCZero TCEC Leagues Season 24Feb – Apr 2023Stockfish (14) + 20 = 64 - 16LCZero TCEC Leagues Season 25Aug – Oct 2023Stockfish (15) + 27 = 50 - 23LCZero TCEC Leagues Season 26May – Jun 2024Stockfish (16) + 31 = 52 - 17LCZero TCEC Leagues Season 27Oct 2024 – Jan 2025Stockfish (17) + 35 = 47 - 18LCZero TCEC Leagues Season 28Jun – Sep 2025Stockfish (18) + 36 = 43 - 21LCZero TCEC Leagues Season 29Jan – Apr 2026Stockfish (19) + 41 = 36 - 23Reckless
TCEC Cups Tournament Date Winner Finals score Runner-up TCEC Cup 1 Oct 2018 Stockfish (1) + 1 = 7 - 0 Houdini TCEC Cup 2 Jan 2019 LCZero (1) + 1 = 7 - 0 Houdini TCEC Cup 3 May 2019 LCZero (2) + 2 = 7 - 1 Stockfish TCEC Cup 4 Oct 2019 Stockfish (2) + 1 = 7 - 0 LCZero TCEC Cup 5 Apr 2020 Stockfish (3) + 1 = 3 - 0 LCZero TCEC Cup 6 Jul 2020 AllieStein (1) + 1 = 3 - 0 LCZero TCEC Cup 7 Nov 2020 Stockfish (4) + 1 = 3 - 0 LCZero TCEC Cup 8 Feb 2021 Stockfish (5) + 1 = 7 - 0 LCZero TCEC Cup 9 Oct 2021 Stockfish (6) + 1 = 3 - 0 LCZero TCEC Cup 10 May 2022 Stockfish (7) + 2 = 9 - 1 KomodoDragon TCEC Cup 11 Jan 2023 LCZero (3) + 2 = 13 - 1 Stockfish TCEC Cup 12 Jul 2023 Stockfish (8) + 10 = 9 - 9 LCZero TCEC Cup 13 Mar 2024 Stockfish (9) + 4 = 17 - 1 LCZero TCEC Cup 14 Oct 2024 Stockfish (10) + 12 = 13 - 11 LCZero TCEC Cup 15 Jun 2025 Stockfish (11) + 6 = 13 - 3 LCZero TCEC Cup 16 Jan 2026 Stockfish (12) + 7 = 12 - 3 LCZero
TCEC Swiss
Tournament Date Winner Runner-up TCEC Swiss 1 Apr 2021 KomodoDragon (1) Stockfish TCEC Swiss 2 Nov – Dec 2021 KomodoDragon (2) Stockfish TCEC Swiss 3 May – Jul 2022 Stockfish (1) LCZero TCEC Swiss 4 Jan – Feb 2023 Stockfish (2) LCZero , KomodoDragon TCEC Swiss 5 Jun - Jul 2023 Stockfish (3) LCZero TCEC Swiss 6 Jan – Feb 2024 LCZero (1) Stockfish TCEC Swiss 7 Sep 2024 LCZero (2) Stockfish TCEC Swiss 8 Apr - Jun 2025 Stockfish (4) LCZero TCEC Swiss 9 Nov - Dec 2025 Stockfish (5) LCZero
TCEC FRC (Fischer Random Chess) Replaced by TCEC FRD. Tournament Date Winner Final/Superfinal score Runner-up TCEC FRC 1 Oct – Nov 2019 Stockfish (1) + 10 = 10 - 0 AllieStein TCEC FRC 2 Nov 2020 Stockfish (2) + 8 = 42 - 0 LCZero TCEC FRC 3 Mar 2021 KomodoDragon (1) + 2 = 47 - 1 Stockfish TCEC FRC 4 Dec 2021 – Jan 2022 Stockfish (3) + 13 = 28 - 9 LCZero TCEC FRC 5 Jul 2022 Stockfish (4) + 17 = 20 - 13 LCZero TCEC FRC 6 May 2023 Stockfish (5) + 15 = 23 - 12 LCZero
TCEC DFRC (double Fischer Random Chess) Replaced by TCEC FRD. In DFRC, the start positions of the pieces are randomized independently for both players. Tournament Date Winner Final score Runner-up TCEC DFRC 1 Jul – Aug 2022 Stockfish (1) + 18 = 23 - 9 LCZero TCEC DFRC 2 May - Jun 2023 Stockfish (2) + 10 = 33 - 7 LCZero
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. Tournament Date Winner Final score Runner-up TCEC FRD 1 Nov - Dec 2023 Stockfish (1) + 11 = 29 - 10 LCZero TCEC FRD 2 Jun - Jul 2024 Stockfish (2) + 20 = 16 - 14 LCZero TCEC FRD 3 Feb 2025 Stockfish (3) + 13 = 25 - 12 LCZero TCEC FRD 4 Sep - Oct 2025 Stockfish (4) + 18 = 18 - 14 LCZero TCEC FRD 5 Apr - May 2026 Stockfish (5) + 21 = 21 - 8 Torch
TCEC 4k Engines are limited to in program size. Tournament Date Winner Final score Runner-up TCEC 4kI Dec 2022 ice4 45.5/48 () 4ku TCEC 4kII May 2023 ice4 + 5 = 15 - 4 4ku TCEC 4kIII Dec 2023 – Jan 2024 4ku + 13 = 30 - 7 ice4 TCEC 4kIV Aug 2024 ice4 + 29 = 20 - 1 4ku TCEC 4kV Apr 2025 ice4 + 29 = 20 - 1 4ku TCEC 4kVI Oct-Nov 2025 ice4 + 11 = 33 - 6 c4ke
Other TCEC tournaments Tournament Date Winner Runner-up TCEC Season 6 FRC Jun – Jul 2014 Stockfish Houdini TCEC Season 9 Rapid Sep 2016 Houdini Komodo TCEC Season 10 Rapid Dec 2017 Stockfish Houdini TCEC Season 10 Blitz Dec 2017 Komodo Stockfish TCEC Season 23 Chess BonusAug 2022Stockfish KomodoDragon
See also Chess engine Computer chess Chess.com Computer Chess Championship World Computer Chess Championship World Computer Speed Chess Championship Dutch Open Computer Chess Championship North American Computer Chess Championship
References
Sources Additional information for Season 4 Additional information for Season 5
TCEC Season 12 report, by Guy Haworth and Nelson Hernandez TCEC Season 13 report, by Guy Haworth and Nelson Hernandez
External links TCEC Live Games Page
TCEC games archive - Scroll down and click on Seasons. chessdom.org with an overview of TCEC's websites