Top Chess Engine Championship (TCEC), the world’s premier championship for computer chess, started its new season with the highly anticipated TCEC Swiss 8 tournament, featuring 44 of the world’s most advanced chess engines. This event surpassed the record set by last season’s Swiss 7, cementing its status as the strongest chess championship ever. With a lineup of elite engines, cutting-edge hardware (record: see the press release), and a global audience of chess enthusiasts, TCEC Swiss 8 promises to deliver a unique show 24/7 over the next months. Follow TCEC Swiss 8 live: Official website / TCEC Chess TV / Lichess / Chessdom live

Stockfish is sole leader after 16 games

After 8 double rounds, or 16 games, Stockfish is the sole leader of TCEC Swiss 8. In R8 Stockfish scored 1,5-0,5 vs Ethreal, while the surprise of the season Integral managed to hold Leela to a 1-1 draw. This was enough for Stockfish to collect 11,0/16, half a point ahead of Leela and 1,5 points ahead of Berserk, KomodoDragon, Integral, and PlentyChess.

Next round will see Stockfish – PlentyChess and Leela Chess Zero – Seer

Top Chess Engine Championship (TCEC), the world’s premier championship for computer chess, started its new season with the highly anticipated TCEC Swiss 8 tournament, featuring 44 of the world’s most advanced chess engines. This event surpassed the record set by last season’s Swiss 7, cementing its status as the strongest chess championship ever. With a lineup of elite engines, cutting-edge hardware (record: see the press release), and a global audience of chess enthusiasts, TCEC Swiss 8 promises to deliver a unique show 24/7 over the next months. Follow TCEC Swiss 8 live: Official website / TCEC Chess TV / Lichess / Chessdom live

After 7 double rounds of TCEC Swiss 8, Stockfish and Leela share the lead with 9,5/14 each. Leela won its match against Boot (replay here), while Stockfish defeated the surprising early leader KomodoDragon, overtaking it in the standings

TCEC Swiss 8 standings after 14 games

Follow Swiss 8 live: Official website / TCEC Chess TV / Innovations in TCEC / Live on Chessdom

Top Chess Engine Championship Swiss 8 participants

Top Chess Engine Championship (TCEC), the world’s premier championship for computer chess, is set to launch its new season with the highly anticipated TCEC Swiss 8 tournament on May 16, 2025, at 19:00 CEST. Featuring 44 of the world’s most advanced chess engines, this event is poised to surpass the record set by last season’s Swiss 7, cementing its status as the strongest chess championship ever. With a lineup of elite engines, cutting-edge hardware, and a global audience of chess enthusiasts, TCEC Swiss 8 promises to deliver a unique show 24/7 over the next months. Follow TCEC Swiss 8 live: Official website / TCEC Chess TV / Lichess / Chessdom live

Hardware boost for chess engines at TCEC aka Kittenware

With high confidence we can say that TCEC has the best hardware setup for chess ever, and you can enjoy it live during TCEC Season 28 and TCEC Swiss 8 thanks to the sponsorship of Kittenkaboodle.

Kanchess comments, “The brand new Kittenware truly belongs in TCEC as most serious top chess engine competition, and is an awesome donation! Can’t wait to see which engines will show how to use this monster hardware with two separate boxes more to their advantage and add some substantial elo” Aloril adds, “Best effort was truly done for both CPU and GPU engines by Kittenkaboodle.“

The GPU boost, benefiting NN engines is the following:

Current new hardware, sponsored by Kittenkaboodle: 8x RTX 5090 (32GB):

• Total memory: 256GB (32GB x 8).
• Total CUDA cores: ~174,080
• Total Tensor cores: ~5,440
• Total power consumption: ~3,600W (450W x 8)

Former hardware, sponsored by Noobpwnftw: 2x A100-PCIE-40GB:

• Total memory: 80GB (40GB x 2).
• Total CUDA cores: 13,824.
• Total Tensor cores: 864.
• Total power consumption: ~500W.

Traditional CPU engines will also enjoy a boost

Current new hardware, sponsored by Kittenkaboodle: AMD EPYC 9754 (2x):

• Type: Server-grade CPU, 4th Gen EPYC (Bergamo, Zen 4c, 5nm).
• Cores/Threads: 128 cores/256 threads per CPU, total 256 cores/512 threads.
• Clock Speed: 2.25 GHz base, 3.1 GHz boost (lower boost due to high core count).
• Cache: 256 MB L3 cache per CPU (512 MB total).
• Performance: ~180,000–200,000 PassMark score per CPU (estimated, ~360,000–400,000 total).

Former hardware, sponsored by Noobpwnftw: Intel Xeon 6230R (2x):

• Type: Server-grade CPU, 3rd Gen Scalable Xeon (Cascade Lake Refresh, 14nm).
• Cores/Threads: 26 cores/52 threads per CPU, total 52 cores/104 threads.
• Clock Speed: 2.1 GHz base, 4.0 GHz turbo.
• Cache: 35.75 MB L3 cache per CPU (71.5 MB total).
• Performance: ~40,000 PassMark score per CPU (estimated, ~80,000 total).

Participants and ELO records

In the three years period between Swiss 1 and Swiss 7, the average ELO of the top 10 participants has increased by 60 points. Now in under 12 months we see another increase of 60 points! In this TCEC Swiss 8 for the first time the chess world will see a 3700+ engine in action, in a top 10 field that exceeds 3621 average ELO!

Stockfish (Elo: 3728): The open-source juggernaut and reigning TCEC Grand Champion, Stockfish has dominated the last seasons, winning the Leagues, Fischer Random, and Cup events. It has just set an unseen rating record and is coming for the only title it lacked last season – the Swiss

LCZero (Elo: 3693): The neural network-based engine, built on the principles of AlphaZero, is coming to TCEC Swiss as defending champion, while aiming to cross the 3700 elo mark during the event

Berserk (Elo: 3646): A rising star in the computer chess world, Berserk has climbed the rankings with its aggressive play and robust performance, making one of the dark horses in Swiss 8.

Obsidian (Elo: 3637): Authored by Gabriele Lombardo who is still U18, Obsidian aims to get minimum a medal at Swiss 8

Ceres (Elo: 3624): A newcomer to the elite ranks in the past season, Ceres has impressed with its performance and is expected to challenge the established giants.

KomodoDragon (Elo: 3615): A veteran engine with TCEC titles in Seasons 5, 7, and 8, KomodoDragon remains a formidable competitor, despite not being actively updated. Once part of the big 3, now KomodoDragon is trying to stay among the best.

Ethereal (Elo: 3613): A consistent performer, Ethereal brings a balanced approach to the board, capable of upsetting higher-rated opponents, while gaining strength every season

Caissa (Elo: 3591): A newer engine that has shown promise in recent seasons, Caissa is poised to make waves in the computer chess world

RubiChess (Elo: 3591): With a solid track record, RubiChess is a reliable contender that can take valuable points from the favorites

Viridithas (Elo: 3570): A lesser-known but rapidly improving engine, Viridithas adds unpredictability to the mix with its unique playing style

Stay tuned for the full list of participants.

More about the Top Chess Engine Championship

TCEC seasons are divided into multiple events, including the traditional Leagues, a knockout Cup, a Fischer Random tournament, and the Swiss tournament.

Since its inception in 2010, TCEC has been the premier platform for pitting the world’s top chess engines against one another in long time-control matches on high-end hardware. Originally known as the Thoresen Chess Engines Competition, TCEC was founded by Martin Thoresen and has been organized by Chessdom since Season 7. The tournament’s reputation as the “Unofficial World Computer Chess Championship” stems from its rigorous format, elite participant lineup, and commitment to showcasing the highest level of computer chess.

Stockfish has played 260 games in the period with 61% score against opposition with average rating of 3625 ELO. That translates into a rating jump from 3672 to 3707 ELO, gained mainly during the events of TCEC Season 27 – Leagues, Cup, and Swiss. (replay TCEC S27 Superfinal here)

More about the ELO record of Stockfish and the upcoming TCEC S28 events at the Chessdom newsletter. This month of April, Chessdom is launching a newsletter that you get DAILY to your mailbox for FREE (signup in the box below)

The closest opponent to Stockfish is the Alpha Zero young sister Leela Chess Zero. It is currently second on the rating list with 3670 ELO. While 37 points are a solid distance in computer chess, Leela Chess Zero actually maintains the pace and stays in the race (see the graph below)

Third is Berserk with 3617 ELO, which briefly interrupted its development, but now is back with fresh power. The biggest danger for Stockfish might come from the 4th engine on the list – lurking from behind is Obsidian with 3612 ELO. This might be close to 100 ELO below the playing strength of the leader, but Obsidian is relatively new engine and is developed by the 16 years old (!!!) Gabriele Lombardo.

This graph shows the progress of Stockfish from the time around the year 2021 to today. It compares the engine to Leela Chess Zero, Stoofvlees, KomodoDragon, and clearly shows the rapid rise of Obsidian. Each Top Chess Engine Championship season is marked on top, with the graph spanning from TCEC Season 19 to TCEC Season 27.

How does Stockfish compare to Stockfish from the past

Stockfish 13 was released February 19, 2021. It is the engine used as a benchmark in the computer rating list. Stockfish 13, which was unbeatable monster back in 2021, currently sits at 17th position in the rating list with 3522 ELO. This is close to 200 ELO less than the current version of Stockfish in just four years!

Furthermore, engines like Clover, Stoofvlees, Seer, Rofchade, Viridithas, Rubichess, Caissa, Ethereal, KomodoDragon, Ceres, Obsidian, Berserk, and Leela Chess Zero all sit ahead of Stockfish 13 in this list, showing the rapid growth and development of the whole computer chess sector

At this moment we have 4KiB (4096 bytes) size engines with playing strength 3100+ (see it to believe it)

More about the Top Chess Engine Championship

The new season of the strongest computer chess championship, where Stockfish will defend its title and ELO record is about to start (Official website / TCEC Twitch TV)

Top Chess Engine Championship, or TCEC for short, is the premier computer chess tournament that has been running since 2010. The use of long time controls high-end hardware results in exceptionally high-quality chess games. The tournament pits the best chess engines – software programs designed to play chess – against each other to determine the strongest among them.

A Top Chess Engine Championship season is a multi-month event that features a series of competitions, typically lasting around 3-4 months, with matches played continuously 24/7 and broadcast live online at the official website. Each season is structured to include several distinct tournaments, testing the engines across various formats and conditions. As of the current format, a season contains:

1. Leagues Season: This is the core event where engines compete in a tiered league system. It starts with lower divisions (like a Qualification League) and progresses through higher divisions, culminating in the Premier Division. Engines move up or down based on their performance, with the top two from the Premier Division advancing to the TCEC Superfinal – a 100-game match to crown the “TCEC Grand Champion.”
2. Cup: A knockout-style tournament featuring 32 engines. It consists of five single-elimination rounds, offering a different competitive dynamic from the league format.
3. Swiss Tournament: A Swiss-system event where all participating engines (often 44 or more) play a set number of rounds (e.g., 11 rounds). Pairings are determined by performance, allowing for exciting matchups and opportunities for underdog engines to shine.
4. Fischer Random Chess (FRC) Tournament: A competition using Chess960 rules aka Fischer Random, lately called and branded as Freestyle chess by Magnus Carlsen, where the starting positions of pieces are randomized. It typically involves preliminary leagues, semifinals, and a final league, with the top two engines advancing to a Superfinal of 50 games.
5. 4k event – included in recent seasons, the TCEC 4k Event is a special competition within the Top Chess Engine Championship that challenges developers to create highly efficient chess engines with a strict size limit of 4 kilobytes (4KiB, or 4096 bytes). This constraint applies to the engine’s executable file or script, making it a unique test of programming skill, optimization, and creativity in computer chess. The idea is to see how strong a chess engine can be when stripped down to an extremely small footprint, harking back to the spirit of early computing challenges like those seen in demo competitions or even the minimalist systems used in the Apollo missions.

Long ago Elon Musk called chess simple and today he continued this topic. Toby Pohlen, founding member of xAI, posted on Twitter/X, “Stockfish plays moves that feel like blunders. We know they’re ~optimal; we’re just incapable of (a-priori) seeing why. A smart human may do things that feel like mistakes. It’s difficult, but try to consider the possibility that they’re right; you just don’t understand why.” [ed.note Stockfish just started its defense of the TCEC Cup] Elon Musk replied, “Chess has a tiny number of degrees of freedom compared to reality: only 64 squares, no fog of war, no tech tree, no terrain differences, same starting pieces & positions every time and you can’t invent new pieces during the game. All of those factors and more are present in reality. So it may seem like someone is close to checkmate in reality, but that doesn’t matter if they suddenly vaporize the opponent’s king with lasers from space that never existed before! Given that there are even winning moves in chess that seem like blunders to humans, then when it comes to understanding winning moves in reality, it is vastly harder to tell.“

Once again Elon Musk strikes the Tweet of the day section, where still Gukesh is the king of this week.

TCEC Swiss 7 will be the first event of the season and will be the strongest chess event (ever!). A total of 44 participants, including the Swiss 6 champion LcZero, the top rated Stockfish and exciting newcomers Ceres, PlentyChess, and Patricia, will battle it out for the title in this record breaking Swiss.

Swiss 7 will be daily live on the official website of TCEC, in video format on TCEC Twitch TV, a broadcast on our favorite game server Lichess, and news reports on Chessdom.

Breaking the ELO record

ELO records depend on multiple factors. They include, but are not limited to, the formula used, the field, the sample size (number of games), and even the configuration (when talking about computer chess). Luckily, TCEC has the precise measurements to detect rating jumps in chess software. And the jump in Swiss 7 is huge! With high confidence we can claim that this is by far the strongest chess event in history.

Putting the record into perspective and “human terms”: imagine a classical tournament at a time where Carlsen and Kasparov close to 3000 ELO and Caruana, Aronian, Firouzja, Topalov, Anand, So, Nakamura, Kramnik, and Giri are all above and around 2900 ELO. Now this is what we are viewing in computer chess at TCEC Swiss 7!

Here is a comparison of the top 10 participants in Swiss 1 and Swiss 7 events. The difference of rating jumps is even bigger among the rest of the participants.

Breaking the participation record

The state of computer chess – thriving! The sector has experienced a recent !boom with the development of new technology and ideas. For the first time ever TCEC had more applications than the event can accommodate. As a result, various engines had to undergo qualifications tournaments, raising the average ELO of the field even more.

TCEC Swiss 7 seeding and participants

This is the full participants list of TCEC Swiss 7 according to seeding. The seed number is determined according to the season rules, starting with the previous champion of TCEC – LcZero

1. LCZero (defending champion of TCEC Swiss 6)
2. Stockfish (Season 26 league champion)
3. Berserk
4. KomodoDragon
5. Ethereal
6. Seer
7. Ceres
8. RubiChess
9. Stoofvlees
10. Caissa
11. Obsidian
12. rofChade
13. Viridithas
14. Igel
15. Revenge
16. Arasan
17. Clover
18. Lizard
19. Velvet
20. PlentyChess
21. Minic
22. Uralochka
23. Stormphrax
24. Ginkgo
25. DeepSjeng
26. BlackMarlin
27. Marvin
28. Altair
29. Equisetum
30. Booot
31. Weiss
32. Tucano
33. Halogen
34. Renegade
35. akimbo
36. Texel
37. Winter
38. Devre
39. ChessFighter
40. Patricia
41. Princhess
42. ice4
43. 4ku
44. Heimdall

Which record is not broken?

TCEC Swiss 7 is part of the 27th edition of TCEC. It is one of the four titles that the engines can compete for, namely the Swiss, FRC, Leagues, and Cup titles. Inherently, every season is stronger than the previous one. Engine chess is booming, authors are more active than ever, technology is developing, ideas are growing. This season and the TCEC Swiss 7 event seems to break all records, but one. It is the TCEC Leagues S11 record, where the Premier Division average rating grew by 150+ ELO points. The average ELO of top 10 engines then was 3351 points, a full 150 points jump.

Another record in sight is the audience. The most viewed season of TCEC was 2 million people audience. Back then it was fueled by Carlsen’s World Chess Championships success. Since then TCEC seasons have crossed 1 million viewers several times, but has never been close to this record.

The match started with Leela taking the lead 2,5-0,5 after winning a game with white in round 1 in Paulsen attack and a second game in round 3 in Sicilian Najdorf. Stockfish reacted, bringing the score level by game 10 and taking a two point lead afterwards. And just when everyone thought Stockfish might be on the way to an easy title, Leela Chess Zero showed that the games from the first rounds were not a coincidence and returned a point.

Replay the decisive games

Lc0 – Stockfish (Center game, Paulsen attack) 1-0
Lc0 – Stockfish (Sicilian Najdorf) 1-0
Stockfish – Lc0 (Sicilian Najdorf) 1-0
Stockfish – Lc0 (King’s Indian, Averbakh system) 1-0
Stockfish – Lc0 (Pirc, Austrian attack) 1-0
Stockfish – Lc0 (French, Tarrash) 1-0
Lc0 – Stockfish (King’s Indian, 5.Be2)

Currently the score is Stockfish 10,5 – Leela Chess Zero 9,5, with a game 22 (a Budapest) going on. Games are going on 24/7 and you can follow then with detailed analysis at the official website here

Unfortunately for the romantics, the first round served up no “Cupsets”. Stoofvlees struggled a little against Marvin, which is always tense because Stoof has a history of “oofing” and losing, but it didn’t happen this time. Round 2 saw a mini-cupset as 14th seed Koivisto put 6th seed Slowchess to the sword, but this wasn’t too surprising either because Koivisto had suffered from a major bug in the previous season and was seeded unusually low as a result. The rest of the matches all proceeded like clockwork as the higher-seeded engines bested their opponents.
But if people were beginning to lose hope, the semifinals brought a real surprise when Stockfish lost an opening to Komodo Dragon. Komodo Dragon is a strong engine, but it has not won an opening against Stockfish for a long time, with the -19 +0 =31 minimatch loss to Stockfish in the Season 22 superfinal an especially bad memory. There was no fairytale comeback this time as Stockfish recovered to win 6-4, but the dropped minimatch did make it seem like the otherwise-untouchable Stockfish can be beaten. Was it a blip, or was it a sign that possibly, just possibly, that Stockfish would fail to win the Cup? In the other semifinal, Lc0 dusted Ethereal away 5-3 to take up the reins as Stockfish’s final opponent. Things started out badly for Leela as Stockfish drew first blood in games 3/4, winning a French Defense, no less. Historically it had generally been Leela who was better at that opening. But in game 7, Leela demonstrated superior positional understanding after Stockfish failed to sense the danger of allowing its Bishop to be forced into a corner.

(Caption) A critical moment in game 7. White’s position is clearly pleasant, and Leela’s +0.97 evaluation is very high by Leela’s standards, but the game isn’t over by any means. Stockfish chose 19…O-O, allowing 20. h6 Bh8. Black’s Bishop is in trouble and the continuation 21. f3 f5 22. g5 made it even more miserable. Although superficially it looks like Black can open a diagonal for the Bishop with …c5, White only has to respond with c3 to keep the Bishop trapped.
This sparkling win tied the match. A tense series of draws later, Leela won game pair 15/16 to win the match. The mighty Stockfish was beaten for the first time in what feels like forever, and Leela won its first title since Season 17.
Next up was the Swiss. This format rewards engines that can reliably beat lower-rated engines, and Leela’s developers submitted a version with dynamic contempt for the first time. This feature is intended to make Leela play for wins against lower-rated opponents, and had already been used to great success by Stockfish (back when Stockfish used handcrafted eval) and Komodo Dragon. For the lower-rated engines, the Swiss took special significance because it affected placing in the Leagues – 22 spots in the Leagues were decided by placing from the previous season, with four more spots going to the top-placing non-qualified engines from the Swiss. 
I could highlight a lot of things, but one thing overshadows them all. In the very first round, Cup winner Leela produced the following brilliancy against QL engine Cheese:

Something had clearly gone wrong with Leela’s dynamic contempt. Needless to say Cheese won easily from this position, and although Leela also won with White to tie the match, it was already behind its rivals – both Stockfish and Komodo Dragon won their opening matches against strong opposition. When the same thing happened to Leela again in round 2 (this time against Drofa), it looked briefly like Leela might not finish in the top 3. Fortunately for Leela fans, the “Leelabug” doesn’t affect Leela’s play against strong engines, and the Swiss format even meant that Leela faced weaker opponents for the next few rounds. Leela steadily fought its way up the table to eventually finish 3rd. For the other members of the Big Three, Stockfish continued to show some weakness when it lost games – but not matches – to Revenge and Scorpio, although it did win the head-to-head against Komodo Dragon. That one point swing, combined with Leela’s dropped half-points against Drofa and Cheese, turned out to be just enough to give Stockfish the tournament victory – its final score of 15.5/22 was exactly one point ahead of Komodo Dragon and Leela on 14.5/22.

For other competitors, the qualifiers to League 2 turned out to be Velvet, Expositor, Wasp, and Uralochka. Velvet played some strong chess, including a 2-0 double kill over Expositor, to finish the highest of the four. Meanwhile, Expositor benefited heavily from the Swiss format when it was paired against the bottom three finishers, scoring 5/6. Its 11.5/22 score actually placed it above League 1 engine Berserk, who had the misfortune of being matched against all of the Big Three. The two 4k engines (so-called because their size is limited to 4 kilobytes) ice4k and 4ku finished solidly last, well off the pace. The 4k handicap is a tough one. 4ku’s developer even deleted the “print eval” line to save space, making 4ku games rather mysterious to watch.

Next up is League 2, where the four qualifiers will face several seasoned competitors, the biggest names being former Premier Division engines Igel and Fritz. Unsurprisingly, both engines are favorites for promotion. Testing is currently under way, and the league is slated to start right after. All games will be played live at https://tcec-chess.com/

Article by Low