Chess Engines and Chess Programs

By Bill Wall

A chess engine is a computer program designed to be used by many chess programs to evaluate a position. A chess engine analyzes chess positions and makes decisions on the best chess moves. Different engines have different playing strengths and often are designed to excel at specific types of evaluations, such as endgames. Today, chess engines can beat 99.9% of human players on modern hardware. Chess engines are not tested in a series of engine vs. engine battles.

Chess engines are good for analyzing games and using it as a playing partner. Chess engines support one or both major protocols called Chess Engine Communication Protocol, such as Tim Mann’s WinBoard (Windows)/XBoard (Unix), or Huber and Meyer-Kahlen’s Universal Chess Interface (UCI). Chess engines increase in playing strength each year due to the increase in processing power that enables calculations to be made to greater depths or ply in a given time. Some chess engines use endgame tablebases to increase their playing strength during the endgame.

A chess engine plays its best move by calculating thousands of positions a second. It is quick and accurate. The average player or beginner cannot do that. He must learn the various concepts and ideas of chess to understand a particular position. The improvement in chess depends on how well you understand a particular position.

A serious player uses computer engines to test new ideas in an opening or in a position, or for analyzing an old game or for preparing against an opponent. Computer engines look at several variations several moves deep to come up with an evaluation. An advanced multi core processor will provide better and faster results.

Different computer engines are good at different aspects of chess. Houdini is good for checking tactics quickly. Komodo is good for positional evaluation and evaluating middlegame positions accurately once the tactics are resolved. Stockfish is good for endgames and in seeing very deep tactics. Strong players use several different engines for checking and verifying.

The two components of chess analysis are search and evaluation. Search is the way that the engine ‘prunes’ the tree of analysis. Modern chess engines trim the list of possible moves dramatically to obtain greater search depth. Evaluation is the set of criteria used by the engine to decipher or evaluate each position encountered during the search.

When preparing for an opponent, serious players use a large chess database to find recent games of that player if that player has known chess games in the database. A chess engine is used to find mistakes or patterns to obtain an advantage in a game against that player.

The first thing a player needs is a chess graphical use interface (GUI). Shane’s Chess Information Database (SCID) is a nice, free GUI that can be used, along with the free Houdini 1.5a engine. ChessBase Light and Arena 3.5 are two other free GUIs. The commercial products include ChessBase, Fritz, Komodo, etc. All of these programs allow you to import and export games with the standard Portable Game Notation (PGN). You need a chess GUI that supports at least one major chess communication protocol (UCI, Winboard, or ChessBase).

Most chess engines do not have their own GUI, but rather console applications that communicate with a GUI, such as WinBoard (Arena 3.5) or XBoard. Arena can load and read Winboard or UCI files, but ChessBase/Fritz can only load UCI files. Arena also comes with several chess engines installed.

Analyzing with a chess engine is straightforward. Just load up a pgn game or select one from a loaded file of such games, highlight the move immediately preceding the point where you wish to begin analyzing and start the engine. Arena allows you to load up a pgn file or and EPD (Extended Position Description) position file.

You can also enter the moves you want to analyze and activate the chess engine analysis. For SCID, click on Tools > analysis Engine. SCID comes with some engines installed. Choose any of them. A chess analysis tab will show dumping the variations and giving it an evaluation. Each variation consists of depth, a numerical evaluation, and the variation moves sequence. The depth is the number of half-moves the engine was calculating (Depth=20 would be 20 half-moves or 10 moves deep). The numerical evaluation of the position is positive if the advantage is for White, negative if the advantage is for Black. Its measurement is usually down to a 1/100^th of a pawn. A zero value means that the position is equal. A value of +1.0 would mean that White is better by the equivalent of one pawn.

The evaluation of the position are displayed for each move. These cause ranking of moves to change as the engine progresses through successive plies. Typically, move rankings change frequently early on, but eventually stabilize and only change by very minute amounts. When an initially lower-ranked move rises toward the top of the heap, it “bubbles up” and is displayed on the top line of the analysis window.

A chess engine helps a player to learn how to play an opening much faster than any other method. Once a player has mastered one sub-variation, he can move on to the next variation. The plan is to try and replicate the chess engine’s play over the board. If you use engines a lot in preparation, then it makes sense to play sharply when you can use the computer’s great power in calculation.

Despite the advantages of the chess engine, one still needs to think on one’s own as opposed to relying on the engine evaluation. The danger of overuse of engines by those who are inexperienced is real. Relying on a chess engine will not improve your play. The chess engine is not a replacement for thinking and improving your chess skill, but it will point out good and bad moves that a player may never have found on his own. If you want to improve, get an instructor. You don’t need a grandmaster, an “A” or “B” player will do. Ask them to help you analyze the game. This gives you reasons, not just answers. And it will help you learn how to analyze. If you rely on engines too much, it will give you answers without helping you understand the answers.

One of the biggest issues with chess engines for the average player is that, from time-to-time, the engine will suggest moves that do not make much sense. They don’t play like a normal human, and sometimes makes bizarre moves. Almost all chess engines play at grandmaster strength and is going to suggest moves the average player would never find. It is easy to say that a player can follow along with an engine’s analysis, observe its suggestions, and try to implement these moves in their own games. But when it comes down to it, the player did no really learn anything at all, and are deceiving themselves into thinking they have learned something from the chess engine.

A player should first spend time analyzing a position without the computer. Once he is satisfied with his analysis, use the chess engine to evaluate the position. Where the chess engine disagrees with the human analysis, try to understand why. An engine is really great for checking for blunders and finding tactical moves. The chess engine can be used to analyze previous games and find the turning point in the games. Chess engines are great at pointing out tactical errors, and that is where they provide the most value.

A chess engine can help average players to understand their mistakes in critical moments, but for most amateurs, their games were decided by blunders. Players should practice to prevent blunders and use a chess engine to understand some tactical and strategical plans. When playing a chess engine, remove all time controls. It is best to relax and take as much time as you need to think through all the intricacies of the position.

Using a chess engine while watching a chess game is very interesting. It gives you a much deeper insight in what top players actually can see and how accurately they evaluate positions. Many tournaments have a live feed that includes engine analysis of the games. At the highest level, in most cases when an engine recommends a particular line of play, the grandmaster plays the same way. The problem with the amateur is that there is no understanding or explanation of why that is the right line of play. There are also times when a chess engine will show that a game is totally winning for one player, but a Super Grandmaster rated over 2700 will miss the correct move and end up losing or drawing the game.

Even if a player comes up with a good plan, executes it successfully, and wins the game, it is always useful to run the moves through a chess engine. The engine will find tactical moves that could have changes the result of the game. When reviewing games with a chess engine, there may have been times where the player debated over two moves for a long period of time. The engine may pass right over that moment as inconsequential.

Many players find tactic trainers (chess problems) more rewarding than playing a chess engine. Playing a chess engine is a war of attrition with tight positional play fighting for tiny advantages, and not very fun. Playing human vs. human allows either or both players to make human errors such as overlooking a tactic or trying something risky, which may not work out. That is much more fun.

Using software to analyze your games is the primary use of computer engines by top players. After every official game they play, they will analyze their games and see where they did wrong and where they could do better. The chess engines are usually proficient in tactics and opening theory. If a top player finds that they did not play the strongest move in one of their positions, next time they will be aware of it and follow the move suggested by the engine. Usually this would happen once again in the opening because middlegames repeat very rarely if played against different opponents.

Learning from a chess engine, when you use it to analyzing your games, is by asking yourself what are the concepts and patterns and what are the positions of consequences that help you find the right move. When a chess engine proposes a move, your thought process should be on understanding how you would come up with the same move. Don’t just simply accept what a chess engine evaluates as the best move. You need to understand why it is a good move.

Chess engines increase in playing strength each year. This is partly due to the increase in processing power that enables calculations to be made to ever greater depths in a given time. Programming techniques have also improved, enabling the engines to be more selective in the lines that they analyze and to acquire a better positional understanding. Top players don’t play strong chess engines necessarily trying to beat it. They play the chess engines to help reinformce opening or endgame ideas.

A chess engine often uses a vast previously computed opening “book” to increase its playing strength for the first several moves up to 20 moves or more in deeply analyzed lines. Some chess engines maintain a database of chess positions, along with previously computed evaluations and best moves.

As engines become stronger, the openings played in over-the-board games have become much more tactical and precise. Top players prepare novelties in their opponent’s pet lines, generate huge trees of analysis, and then try to memorize all the different lines. Because some lines have been analyzed out (as deep as 35 moves), players have to find new ideas and try to get the opponent out of book. This has become much more important, especially when playing against an opponent known for his thorough preparation. Thanks to huge chess databases, players are much more aware of what lines have already been played. It would be hard to catch strong grandmasters in traps nowadays.

Some chess engines use endgame tablebases to increase their playing strength during the endgame. Endgame tablebases have enlarged the number of positions known to be theoretically won or drawn. The most widely used tablebases are the 6 piece Nalimov tables and the 7 piece Lomonosov tables (available to members on the ChessOK website). Complete tablebases consume a huge amount of hard drive space, in the terabyte range.

Top players spend a fair amount of time preparing openings and working on their weak areas. They use chess engines to draw up a repertoire, to test their memory of their repertoire, to go through tactical puzzles, to work on positional exercises, to review and analyze games, to compile statistics on their own performance in various openings, and to research their opponent’s openings and weak spots. It is nearly useless to play full games against the top engines, but some players use weaker chess engines as sparring partners for playing out positions or endgames. For computer engines, it is much harder to simulate a “human” style than just playing good. If you want to improve your play against humans, play against humans and use the engines to analyze your games.

Currently, the top three chess engines are Komodo 9.2, Stockfish 6 (open source), and Houdini 4. Other strong engines include Fritz, Rybka, Hiarcs, Junior, and Crafty. There are over 100 strong chess engines available on the Internet, many offered as free downloads. There are several rating lists for chess engines (CCRL, CEGT, IPON, SSDF). These ratings are derived primarily from engine vs. engine “timed” tournaments on identical hardware. Many of the free download engines are older, lower-rated versions of their more established programs. Some are free for a trial period, after which they must be purchased. Other chess engines are beta versions of new engines from little-known programmers trying to establish their brand in a highly competitive market.

Generally, you improve the most if you play against opponents slightly stronger than you. Chess engines are usually way too strong for most people. You need to adapt by upping your game and develop a positional understanding of the game.

Some players use their chess engine to play correspondence chess. In today’s correspondence chess, a non-engine player will lose to an engine-assisted player every time. Many sites where you can play chess online do not allow computer-assisted play. It is considered cheating, and if caught, usually means a ban from the site. Unlike conventional chess, when engine vs. engine play occurs, it is extremely difficult to recover from even one weak move. Once your opponent’s engine obtains a certain numerical advantage, it will steadily outplay your engine every time. The only time a human has to think when using an engine is where the top two (or more) ranked moves are identical, or nearly identical and the engine cannot break the tie, no matter how many plies have been examined.

The first record of the chess engine was around 1994. The Chess Engine Communication Protocol was designed by Tim Mann, author of XBoard. It was initially intended to communicate with the GNU Chess engine, which only accepted text input and produced text output. The protocol was called Winboard for Windows systems and XBoard for Unix systems.

The UCI standard was developed in November 2000. The standard was worked out by Stephan Meyer-Kahlen (1968- ), a German programmer. The UCI standard was presented by Rudolf Huber, a German computer scientist. The UCI protocol, a rival to the older XBoard/WinBoard Communication protocol, was used by only a few programs until ChessBase began to support this protocol in 2002.

In 1990 World Champion Anatoly Karpov lost to MEPHISTO in a simultaneous exhibition in Munich. MEPHISTO also beat grandmasters Robert Huebner and David Bronstein. MEPHISTO won the German blitz championship and earned an International Master norm by scoring 7-4 in the Dortmund Open.

In 1992 Kasparov played Fritz 2 in a 5 minute game match in Cologne, Germany. Kasparov won the match with 6 wins, 1 draw, and 4 losses. This was the first time a program defeated a world champion at speed chess.

In March, 1993 GM Judit Polgar lost to Deep Thought in a 30 minute game.

In 1994 WCHESS became the first computer to outperform grandmasters at the Harvard Cup in Boston.

In 1994 Kasparov lost to Fritz 3 in Munich in a blitz tournament. The program also defeated Anand, Short, Gelfand, and Kramnik. Grandmaster Robert Huebner refused to play it and lost on forfeit, the first time a GM has forfeited to a computer. Kasparov played a second match with Fritz 3, and won with 4 wins, 2 draws, and no losses.

At the 1994 Intel Speed Chess Grand Prix in London, Kasparov lost to Chess Genius 2.95 in a 25 minute game. This eliminated Kasparov from the tournament.

The 13th World Micro Computer Chess Championship (WMCCC) was held in Paderborn, Germany in October, 1995. It was won by MChess Pro 5.0 (by Marty Hirsch) after a playoff with Chess Genius (by Richard Lang).

The 8th World Computer Chess Championships were held in May, 1995 in Hong Kong. The event was won by Fritz, after it won a playoff game against StarSocrates.

In November 1995, Kasparov beat Fritz 4 in London with a win and a draw. He then played Genius 3.0 in Cologne and won the match with one win and one draw.

The 6th Harvard Cup Human Versus Computer chess challenge was held in New York in December, 1995. The Grandmasters won with a score of 23.5 to the computers 12.5 score. The computers scored 35%, a slight decrease in performance from 1994. Joel Benjamin and Michael Rohde had the best human scores with 4.5 out of 6. The best machine was Virtual Chess (I-Motion Interactive) with 3.5 out of 6.

In February 1996, Garry Kasparov beat IBM's DEEP BLUE chess computer 4-2 in Philadelphia. Deep Blue won the first game, becoming the first computer ever to beat a world chess champion at tournament level under serious tournament conditions. Deep Blue was calculating 50 billion positions every 3 minutes. Kasparov was calculating 10 positions every 3 minutes. DEEP BLUE had 200 processors.

The 11th AEGON Computer Chess Tournament (Mankind vs. Machine) was held on April 10-17, 1996 in The Hague, Netherlands. There were 50 masters, International Masters, and Grandmasters and 50 computers (most playing on HP Pentium-166 machines with 16MB of RAM). Yasser Seirawan won the event with 6 straight wins and no losses. The best computer was QUEST, with 4.5/6 and a 2652 performance rating. The machines won with 162.5 points versus the humans with 137.5 points.

The 14th World Microcomputer chess championship was held in Jakarta in October, 1996. It was won by SHREDDER, followed by FERRET.

On May 11 1997, DEEP BLUE defeated Garry Kasparov in a 6 game match held in New York. This was the first time a computer defeated a reigning world champion in a classical chess match. DEEP BLUE had 30 IBM RS-6000 SP processors coupled to 480 chess chips. It could evaluate 200 million moves per second.

In November, 1997 Junior won the 15th World Micro Computer Championship. The event was held in Paris.

In 1997, the Allen Newell Medal for Research Excellence went to several people involved in computer chess. Ken Thompson and Joe Condon won for their pioneering work on Belle, the first master in 1983. Richard Greenblatt won for having developed MacHack VI in 1967, the first Class C chess computer. Lawrence Atkin and David Slate won for developing CHESS 4.7, the first Class B and first Expert chess computer from 1970 to 1978. Murray Campbell, Carl Ebeling, and Gordon Goetsch won for developing Hitech, the first Senior Master computer in 1988. Hans Berliner won for all his work in computer chess. Feng Hsu won for developing Deep Thought, the first chess computer that performed at a Grandmaster level in 1988. Thomas Anantharaman, Michael Browne, Murray Campbell, and Andreas Nowatzyk won for their work on Deep Thought in 1997. Murray Campbell, A. Joseph Hoane, Jr, and Feng Hsu won for their work on Deep Blue which defeated Garry Kasparov in 1997.

In 1997 the $100,000 Fredkin Award went to the inventors of Deep Blue - Feng Hsu, Murray Campbell, and Joseph Hoane, of IBM. Their program defeated Kasparov.

The 9th World Computer Championship was held in Paderborn, Germany from June 14, 1999 to June 19, 1999. The winner was Shredder. This was also the 16th World Microcomputer Chess Championship, won by Shredder.

In 1999 the highest rated chess computer is Hiarcs 7.0, followed by Fritz 5.32, Fritz 5.0, Junior 5.0, Nimzo 98, Hiarcs 6.0, Rebel 9.0, MChess Pro 7.1, Rebel 8.0, and MChess Pro 6.0 (based on SSDF ratings as of Jan 28, 1999).

In August 2000, Deep Junior took part in the Super-Grandmaster tournament in Dortmund. It scored 50 percent and a performance rating of 2703.

In 2000 the 17th World Microcomputer Chess Championship was held in London. It was won by Shredder.

In August, 2001, Deep Junior won the World Micro Computer Championship. The event was held in the Netherlands.

In November, 2000, the Universal Chess Interface (UCI) was released. It was designed and developed by Rudolf Huber and Stefan Meyer-Kahlen. It has replace the older Chess Engine Communication Protocol (Winboard/XBoard).

In January 2002, Chessbase began supporting the UCI protocol, which soon became the standard.

From May 13 to May 18, 2002, a match between Grandmaster Mikhail Gurevich and Junior 7 was held in Greece. Junior won with 3 wins and 1 draw.

On July 6-11, 2002, the 10th World Computer Championship was held in Maastricht, Netherlands. The winner was Deep Junior after a playoff with Shredder.

In October, 2002, Kramnik drew a match with Deep Fritz in Bahrain with a 4-4 score. Kramnik won games 2 and 3. Deep Fritz won games 5 and 6. The rest of the games (1, 7, and 8) were drawn.

From January 26 to February 7, 2003, Kasparov played Deep Junior 7 in New York. The match ended in a draw. Kasparov won game 1. Deep Junior won game 3. The rest of the games (games 2, 4, 5, and 6) were drawn. This was the first time that a man/machine competition was sanctioned by FIDE, the World Chess Federation. Deep Junior took 10 years to program by Tel Aviv programmers Amir Ban and Shay Bushinksy. It can evaluate 3 million moves a second, and positions 15 moves deep.

On November 11-18, 2003, Kasparov played X3dFritz in New York. The match was tied 2-2. Fritz won the 2nd game. Kasparov won the 3rd game. Games 1 and 4 were drawn. It was the first official world chess championship in total virtual reality, played in 3-D.

The 11th World Computer Chess Championship was held in Graz from November 22 to November 30, 2003. It was won by Shredder after a play-off with Deep Fritz. 3rd place went to Brutus, which evolved into Hydra.

In 2003 the top chess computers were Shredder 7.04 (2810), Shredder 7.0 (2770), Fritz 8.0 (2762), Deep Fritz 7.0 (2761), Fritz 7.0 (2742), Shredder 6.0 (2724), and Chess Tiger 15.0 (2720).

The 12th World Computer Chess Championship was held at Bar-llan University in Ramat-Gan, Israel from July 4 to July 12, 2004. It was won by Deep Junior (programmed by Amir Ban and Shay Bushinsky). Shredder took 2nd place, followed by Diep. Shredder won the 12th World Computer Speed Chess Championship. Crafty took 2nd place.

In 2004, Hydra defeated GM Evgeny Vladimirov with 3 wins and 1 draw. It then defeated former FIDE world champion Ruslan Ponomariov (rated 2710) in a 2-game match, winning both games.

In June, 2005, Hydra beat Michael Adams, the 7th ranked chess player in the world. Hydra won 5 games and drew one game.

The 13th World Computer Chess Championship was held at Reykjavik University in Iceland from August 13 to August 21, 2005. It was won by Zappa (programmed by Anthony Cozzie). 2nd place went to Fruit. Shredder won the speed championship, followed by Zappa.

In 2005, a team of computers (Hydra, Deep Junior, and Fritz) beat Vesilin Topalov, Ruslan Ponomariov, and Sergey Karjakin (average rating 2681) in a match by the score of 8.5 to 3.5.

The 14th World Computer Chess Championship was held in Turin, Italy from May 24 through June 1, 2006. It was won by Junior, rated at 2800, with a score of 9 out of 11. 2nd place went to Shredder (2810), followed by Rajlich (2820).

In December, 2006, world champion Vladimir Kramnik was defeated by Deep Fritz, which won with a 4-2 score (2 wins and 4 draws).

The 15th World Computer Chess Championship was held in June, 2007, in Amsterdam and sponsored by the International Computer Games Association (ICGA). The winner was the USA program Rybka ("little fish"), programmed by International Master Vasik Rajlich, with a score of 10 out of 11 (defeating Shredder in the last round). 2nd place went to the USA program Zappa, programmed by Anthony Cozziem with 9 points. 3rd place went to Loop, with 7.5 points. Defending champion Junior, nor Fritz, did not participate. The German program Shredder won the blitz world championship.

In June, 2007, the "Ultimate Computer Challenge" was held in Elista. Deep Junior defeated Deep Fritz with the score of 4-2 (2 wins, 4 draws).

In August, 2007, Grandmaster Joel Benjamin played a match with Rybka in which Rybka played without one of its pawns (pawn odds). Rybka won the match 4.5 - 3.5 (2 wins, 1 loss, 5 draws for Rybka).

In December, 2007, Hiarcs won over tie breaks against Rybka, with a score of 5.5 out of 7 at the 17th International Paderborn Computer Chess Championship.

In January, 2008, Rybka defeated GM Joel Benjamin with a 6-2 score. Joel had White in every game. Also, every draw was scored as a win for Benjamin.

In March, 2008, Rybka and Dzindzichashvili drew 4-4 in their match. Rybka won 2, lost 2, with 4 draws. Dzindzichashvili had White every game and Rybka played without one of its pawns in every game.

The 16th World Computer Chess Championship was held in Beijing, China in September, 2008 and won by Rybka, followed by Hiarcs and Junior.

The 17^th World Computer Chess Championship was held in Pamplona, Spain in May, 2009 and won by Rybka, followed by a 3-ways tie for 2^nd between Shredder, Junior, and Deep Sjeng.

In 2009, Pocket Fritz 4 won the Copa Mercosur chess tournament with a 9.5 out of 10 score.

The 18^th World Computer Chess Championship was held in Kanazawa, Japan in 2010 and won by Rybka, followed by Rondo and Thinker. The blitz tournament was also won by Rybka with 8/9 score.

From 2010, a new tournament was introduced, called the World Chess Software Championship. All chess programs had to run on machines with identical hardware specifications. The winner for 2010 was Shredder.

Rybka won the 30^th Dutch Computer Chess Championship in Leiden, followed by Spike, Deep Sjeng and Hiarcs.

In June, 2011, the International Computer Games Association (ICGA) stripped Rybka of all its World Computer Chess Championship titles after discovering that Vasik Rajlicj, who programmed Rybka, incorporated and plagiarized elements of older programs (Crafty and Fruit), without attribution. Rajlicj violated the rule that each program must be the original work of the entering developers. Programming teams whose code from others must name all other authors, or the source of such code, in their submission details.

In 2006, the program “Rajlich” took 2^nd-3^rd place in the world computer chess championship. That has now been annulled. 2^nd place now goes to Shredder and 3^rd place goes to Zappa.

The 1^st places and World Computer Chess Champion titles that was awarded to the program Rybka from 2007 through 2010 are all annulled, The revised titles are: 2007 – Zappa (World Champion); 2008 – Hiarcs (World Champion); 2009 – Junior, Shredder, and Deep Sjeng (Joint World Champions); 2010 – Rondo and Thinker (Joint World Champions. In 2011 and 2013, Junior won the World Computer Chess Championship. In 2015, Jonny won the World Computer Chess Championship, held in Leiden.

In 2010, Shredder won the World Chess Software Championship.

In 2011 and 2013, HIARCS won the World Chess Software Championship.

In 2015, Shredder won the World Chess Software Championship, held in Leiden. Its hardware was an Intel quad core i7.

Modern top chess engines that run on a regular PC are significantly stronger than Deep Blue that defeated Kasparov in 1997. Deep Blue was a dedicated computer for the sole purpose of playing chess. It could calculate 200 million chess positions per second. But today’s chess engines do not calculate that fast. But they are better than Deep Blue because their search tree pruning and position evaluation functions have vastly improved since the Deep Blue days. The chess engines that are free or cost less than $100 can beat 99% of all chess players, including Deep Blue. Today’s chess engines are capable of finding the best moves with significantly less work than Deep Blue was.

Chess engines and ratings

Abrok 5.0 – 2434. Abrok is a Winboard (WB) and UCI engine from Germany.

Absolute Zero 2.4 – 2236

ACE

ACE(2)

AdaChess 2.0

Adam 3.2 - 2129

Adam 3.3 – 2207

Adamant 1.7 - 1790

AdroitChess 0.3 – 1986

AdroitChess 0.4

Alice 06.06.27

Alice 0.99.2 - 2328

Alaric 707 – 2661. UCI (Alaric.exe) and Winboard engine (AlaricWB.exe).

Alarm 0.93.1 - 2147

Alf 1.09 – 2190

Alfil 13.1

Alfil 15.7 – 3154

Alfil 15.8.16 (UCI)

AliBaba 1.40 - 1800

AliChess 4.25 – 2283

Alex 2.03 - 2198

Alex 2.14a – 2382

Amateur 2.82 – 2382

Amundsen 0.80 – 2329 (Winboard only)

Amy 0.87b – 2390 (winboard)

Amyan 1.72 – 2588

Anaconda 2.0.1 – 2554

Anatoli 0.35 - 2478

Andscacs 0.82 – 3095

Andychess3

Anechka 0.08 - 2288

AnMon 5.66 – 2538

anMon 5.75

Ant 2006 – 2295

Apep 010

Arabian Knight 1.5.4

Arasan 17.5 – 2944

Arasan 18.1

Ares 1.005 – 2414

Aretar 1.0

Arics 0.95a

Arion 1.7 - 2340

Aristarch 4.50 - 2598

Arminius – 2653

Asterisk 0.6 – 2325

Atak 6.8 – 2233

Atlas 2.20 - 2197

Atlas 3.80 – 2839

Atlas Too 0.42

Averno 0.81 – 2317

Ayito -2243

Bagatur 1.3a – 2320

Barbarossa 0.3.0 - 2033

Battle Chess

BBChess 1.3b – 2477

Bearded N 44.2 – 2217

Bearded N 44.5

Belka 1.8.20

Beowulf 2.4a – 2246

BeRoChess 1.00 - 1840

Betsabe II 1.47 – 2438

BibiChess 0.5 - 1995

BigLion 2.23 - 2061

BikJump 2.01 – 2112

Bismark 1.4

Bison 9.11 – 2755

Bitfoot 1.0 – 2421

BlackAndRight

BlackBishop 1.0 - 2194

BlackMamba 2.0 – 3138

Blunderer 1.1

Bobcat 6.4b 2872

Booot 5.2.0 - 2899

Bouquet 1.8 – 3154

BremboCE 0.6.2

Bright 0.4a – 2902

Bruja 1.9.1 - 2472

Brutus 8.05 – 2571

BSC 3.9 - 1991

Bubble 1.5 - 2021

BugChess2 1.9 – 2847

Butcher 1.61 – 2316

Butcher 1.64

Buzz – 2235

Byak 8.10.40

Calculon

Carnivor 1.0

CaveChess

Counter 1.2 - 2467

Capivara – 2558

Carballo 1.3 – 2456

Centaur

Cerebro 3.03d – 2478

Chaturanga 2.4.3 - 2282

Cheese 1.7 - 2677

Cheng 4.39 – 3032

Chesley e323 - 2177

Chess Challenger

Chess Tiger – 2704

Chess Tiger 15.0 – 2720

Chess(2) 4.1a

Chess3 0.1

Chess4J 2.0

Chesley – 2163

ChessAlex 2.0r4 – 2220

ChessBrain 1.1

Chesser

ChessGenius

ChessKISS 1.7 – 2209

Chessmaster 11 – 2722

ChessMaster 2100

ChessMaster 5500

ChessMaster 9000

ChessMind 0.82 – 2009

ChessNovice

ChessOne

Chezzz 1.0.3 - 2296

Chiron 2 – 3096

Chispa 4.0.3 - 2261

Chronos 1.9.9 – 2743

Cinnamon 1.2b - 1811

Clarabit 1.00 – 2107

Claudia 0.2

Clubfoot 1.0.124

Clueless 1.4 – 1903

CmcChess 2.6

Coiled 0.2b - 1793

Colossus 2008b - 2642

Comet B50

Comet B68 – 2387

Comstock

Conqueror 1.2

Counter 1.2 - 2194

CPW 1.1

Crabby 1.0.0

Crafty 17.13

Crafty 19.01

Crafty 20.14

Crafty 23.0

Crafty 23.01

Crafty 23.1 – 2518

Crafty 23.3 - 2572

Crafty 23.4

Crafty 23.8 – 2913

Crafty 24.1

Critter 1.6a

CuckooChess 1.12 – 2589

Cupcake 1.1a – 1995

CvpChessEngine

CyberPagno 2.2 – 2327

CyberPagno 2.3

Cyclone

Cyrano – 2646

Dabbaba 5.67 – 1969

Dabbaba 7.49

DanaSah 5.07 – 2560

DarkTemplar 0.1.1

Darky 0.5e

Daydreamer 1.75

DCP 0.76

Deep Bug 1.0

Deep Fritz 7.0 - 2761

Deep Fritz 14 – 3085

Deep Hiarcs 14

Deep Junior 13 – 3039

Deep Junior 13.8.04

Deep Shredder 12 – 3030

Deep Sjeng – 2943

Deep Sjeng 2.7 32b - 2530

Deep Smash 1.0.3a

DeepBrutePOS

Deepov 0.2

DeepSaros

Defeo 0.4.2

Delfi 5.4 - 2727

Delphil 3.2 – 2501

Demon

Deuterium 14.3.34.130 – 2901

Diablo 0.5.1 – 2406

Diep

Dirty - 2808

DisasterArea 1.54 - 2833

DiscoCheck 5.2 – 2911

DiscoCheck 5.2.1

Djinn 1.021 – 2654

DokChess 0.1

Dolphin 1.0 – 2223

DON

Donna 3.1 – 2512

Dorky 4.3 – 2444

Dragon 4.6 – 2404

Dreamer 0.21

Eagle 0.7.5 - 1757

Ecce 0.33

Ecce 1.0 - 2052

ECE 12.01 – 2311

Eden 0.0.13

Eeyore 1.52 – 2441

Eia 0.3

Elekto 1.2

Embla 0.5

Equinox 3.20 64-bit – 3190

E.T. Chess – 2648

EveAnn 1.71

Exacto – 2239

ExCE

EXchess 7.51b – 2944

EXchess 7.71

Faile 1.4 - 1807

Fairy-Max 4.8

Felpo

Feuerstein - 2231

Fire 4 64-bit – 3209

Firebird

Firenzina 2.4.3

Firefly 2.6.0 - 2187

FireFly 2.7.0 – 2278

Fischer 1.00

Fischerle 0.9.65 - 2281

Fizbo 1.5 – 3011

Flip4IT

Floyd 0.6

Floyd 0.7

Flux 2.2.1 – 2346

Fly By Knight 0.3.0

Fortress 1.62 - 2139

Francesca – 2558

Frank-Walter 1.0.8

Frenzee 3.5 – 2779

Fridolin 2.0 – 2578

Frittle 1.0

Fritz 5

Fritz 5.32

Fritz 6

Fritz 6 Light

Fritz 7.0 - 2742

Fritz 8.0 - 2762

Fritz 10

Fritz 11

Fritz 12

Fritz 13

Fritz 15

Fruit

Fruit Reloaded 2.1

Fruitfly 1.1.1

Gaia 3.5 – 2422

Galjoen 0.31

Gambit 1.0.3

Gandalf 6 – 2630

GarboChess 3.0 - 2575

Gaviota 1.0 – 2953

GChess IV – 1894

Genesis 2.0 - 2175

Ghost 2.0 – 2474

Ghost 2.0.2

Gibbon 2.60a – 2317

Gibbon 2.69

Giraffe – 2432

GiuChess 1.0

GK 0.90 - 2115

Gladiator 0.0.1

Glass 2.0 – 2595

Glaurung

GnuCheese 1.0

GNU Chess 1.00 - 2796

GNU Chess 5.60 – 2819

GNU Chess 6.2.2

Godel 3.4.9 – 2733

Gogobello 0.11 – 1895

GopherCheck

Gosu 0.16 - 2385

Green Light Chess 3.01.2.2 - 2477

GreKo 12.8 – 2600

GreKo 13.1

Grizzly 2.08

Gromit 3.0

Gull 2.8

Gull 3 64-bit – 3196

GullChess 3

Gunborg 1.35

iCE 2.0 - 2897

Hakkapeliita 3.0 – 2952

Hamsters 0.7 - 2623

Hannibal 1.5 – 3113

Haskak 0.1

Heavy 1.3 - 1702

Heracles – 1969

Heracles 0.6.16 - 1738

Heretic 0.3

Hermann 2.8 – 2518

Hiarcs 6.0

Hiarcs 7.0

Hiarcs 8

Hiarcs 9

Hiarcs 13

Hiarcs 14 – 3067

HoiChess 0.12

Homer 2.01

Horizon 4.4 - 2382

Houdini 1.5a

Houdini 3

Houdini 4 64-bit – 3262

Husser 0.1 - 2124

Hussar 0.4 – 2442

iCE 2.0

Ifrit m1.8 – 2389

Igorrit

InmiChess 3.06 - 2169

IntelliChess 1.0

Iota 0.1

IPPOLIT

IvanHoe

Jabba 1.0 – 2074

JaksaH 1.12

Jan William 1.13 - 1814

Javalin 2.0

JavaRival 00.94

Jazz 721 – 2379

Jazz r840 - 2195

JChess 1.0

Jellyfish 1.1 – 2574

JFresh 0.1a

JikChess 0.02 – 2570

Joker 1.1.14 - 2293

Jonny 4.00 – 2835

Junior

Junior 5.0

Junior 7

Junior 13.8.04

K2 0.75 – 2485

Kaissa 2 1.8a

Kenny 0.1.1.0

Kenny ClassIQ 0.3

King’s Out 0.2.42

Kitteneitor 0.22.1

Kiwi – 2410

KMTChess – 2222

KnightCap 3.7

KnightDreamer 3.3

KnightX 1.92 – 2318

KnockOut - 2145

Komodo 5

Komodo 8

Komodo 9.2 64-bit – 3351

Krudo 0.14b

Ktulu 9 – 2753

Kurt – 2177

Laser 0.2.1

Latista 1.5 - 2187

LChess

Leonidas r83 - 1814

Lime 66 - 2164

Little Goliath Evolution 3.12 – 2506

Little Thought 1.052 – 2500

Little Wing 0.0.1

Loop M1-T – 2855

Lopez 01

Lozza 1.15 – 2339

Macromix 2.01

MadChess 2.0 – 2369

Madeleine 0.2 - 2200

Madlenka

MagnumChess 4.0.0

Mainsworthy 141

Mango Paola Ajedrez 4.1 – 2245

Markovian

Marvin 1.3.0 - 1967

Matacz 1.3 – 2480

Matheus 2.3 - 2028

Matilde 2008 – 2291

MatMoi - 1936

Maverick 1.0 – 2501

Maverick 1.5

MChess Pro 6.0

MChess Pro 7.1

mchess2 1.02.00

Mediocre 0.4 – 2309

Mediocre 0.5

Mephisto

Mephisto Gideon 1993

Micro-Max 4.8 – 1937

Milady 3.25

Minace 1.0

MiniChessAI 1.20

miniMardi 1.3

MinkoChess 1.3 – 2902

Minnow

Monarch 1.7 – 2024

Monik 2.2.3 – 1956

Morphy 3.22 - 1771

MorphyChess 1.0.5

Movei – 2667

Mr Chess 2.1 - 1704

Murka 3 – 2830

Muse – 2414

Mustang 4.97 – 2029

MyTeacheR 0.2

Mychess

Myrddin 0.87 - 2364

N2 0.4 – 2590

NagaSkaki 5.112 – 2169

nanoSzachy 4.0 – 2535

nanoSzachy 4.1

Napoleon 1.5.0 – 2119

Napoleon 1.6.0

Naraku – 2778

Natwarial 0.14 - 2299

Naum 4.6 – 3105

Nebiyu 1.45

Nebula 2.0 -2726

Nejmet 3.07

Nemeton 1.1 – 2322

Nemeton 1.2

Nemo 1.0.1 – 2855

Nesik 0.7.0 - 2146

neuroGrape 1.1

Neurone XXIV

Neurosis 2.3 - 2185

Neurosis 2.5 – 2199

NeuroStock 2.01

NG-Play 9.85 – 2187

NG-Play 9.8.6

Nimzo 8 – 2510

Nimzo 98

NirvanaChess 2.2 64-bit – 3174

NoraGrace 2.0 – 2595

Numbit 01.2

Numpty

OBender – 2184

Oberon 0.04

Octochess – 2832

OliThink 5.3.2 – 2379

OliveChess 0.2.7

Onno 1.2.70 – 2945

Orion 0.2 – 2270

P4win 2.02

PanChess

Parrot - 2130

Patzer 3.80 - 2391

Pawny 1.1 – 2699

pChess 2.0

Pedone 1.3 – 2835

Pepito 1.59 - 2485

Petir 4.39 – 2595

Phalanx XXIV - 2533

Pharon 3.5.1 – 2659

Philou 3.7.1 – 2649

pikoSzachy 3.4 – 2391

pikoSzachy 4.1

pikoSzachy Extreme

Plisk 0.2.6 – 2347

PLP - 2041

Popochin 2.9

Pocket Fritz 4

Portfish

PostModernist 1016 – 2427

Powder 1.5.1

Powerchess

Predateur 2.2 – 1853

Predateur 2.2.1

ProChess 1.02 - 2184

ProDeo 1.86 – 2702

Project Invincible 2.10

Prophet 2.0 - 2178

Protector 1.9.0 – 3162

Protej 0.5.8c - 2242

Pseudo 0.7c – 2590

Psion

Pulse Chess 1.61.

Pupsi2 0.09 – 2489

Purple Haze 2.1.0

Pwned 1.3

Pychess 0.12.1

Pyotr 0.6

Quark - 2474

Quazar 0.4 – 2909

Queen 4.03 – 2406

Raffaela 2.1.5

Raijlich – 2820

Rainbow Serpent build 179

Ramjet 0.10 - 1739

Ramjet 0.12

Ranita 2.4 - 1704

RattateChess – 2247

RBrChess 3.2

Rebel

Rebel 5.0

Rebel 8.0

Rebel 9.0

Rebel 13

RedQueen 1.1.3 – 2666

RedQueen 1.1.97

Reger 0.09 - 1915

Rex

Rhetoric 1.4.1 – 2776

Rival 1.18 – 1966

RobboLito 0.21

Robocide

Roce - 1718

Rocinante 2.0

Rodent 1.7 – 2849

Rodin 7.0 – 2598

RomiChess 2402

Rondo

Roque 2.1 - 1717

Rotor 0.7a – 2630

Rotor 0.8

RubyKnight 0.2.0

Ruffian 1.0.5

Ruffian 2.1.0 – 2624

Rybka 2.3.2a

Rybka 3

Rybka 3.1

Rybka 4 – 3161

Sage 3.53 – 2379

SamChess 1.0 - 1795

Sargon

Saros

Satana 2.1.14

Sayuri

Schola 1.1.0 - 1988

Schooner 1.4.2 - 2209

Scorpio 2.7.6 – 2884

Scorpio 2.7.7

SdBC 0.5.15.1

SecondChess 0.1

Senpai 1.0 – 3038

Shallow 1.0 - 2191

Shallow rev. 688 2407

SharpChess2 2.6.9

Shredder 6.0 - 2724

Shredder 7.0 - 2770

Shredder 7.04 - 2810

Shredder 12

Shutranj

SilChess 3.1

SillyChess

Simplex – 2396

Sjaak II 1.0

Sjaal 5.24 - 1712

Sjakk 2.2 – 2636

Skotz 0.2.1

Slibo - 2021

Sloppy 0.2.2 - 2610

Slow Chess Blitz – 2639

SM-FIDE 760

Small Potato 0.7.0

SmarThink 1.70 – 2922

Smash 1.0.3 – 1965

smex 583

Smirf

Snail 4.013 - 1755

Snitch 1.6.2 – 2439

Socrates

Soldat III 0.178 - 2064

Sorgenkind 0.4 - 2383

SOS 5.1 - 2559

Spark 1.0 – 2980

Spike 1.2 - 2554

Spike 1.4 Leiden – 3030

SpiderChess – 2479

Sting SF 5

Stockfish 1.7.1

Stockfish 5

Stockfish 6 64-bit – 3308 (open source, GPL license available on GitHub)

Strelka

Strelka 5

Strelka 5.5 – 3113

Strelka 6

SugaR PrO 1.2

Sunfish

Sungorus 1.4 – 2310

Sunsetter 10.3 - 2153

Superpawn build 108

Surprise 4.3 – 1885

Talvmenni 0.1

Tao 5.6 – 2500

Testina 3c

Texel 1.05 – 3102

The Baron 3.29 – 2867

The Turk 0.3

Thinker

Thinker 5.4d – 2939

Thor’s Hammer 2.28 - 2375

Tigran 2.4n – 2391

Timea

TJchess 1.01 – 2365

TJchess 1.1

Toga II – 2929

Toga Returns 1.1b

Tornado 6.0 2903

Tornado 7

Trace 1.36 – 2476

TrappyBeowulf rev 11

TSCP 1.81

Tucano 5.00 – 2677

Turgenev rev. 32

Tursas 0.2

Tytan 9.3 - 2364

Twisted Logic – 2763

Typhoon 1.00 - 2437

Ufim 8.02 – 2540

Unidexter

Uralochka 1.1b - 2213

Vajolet2 2.0 – 2919

Vapor 0.02

Vice 1.1

Violet 3.0

Virutor 1.1.2

Vitruvius 1.1

Warrior 1.0.3 - 1899

Waxman 2014 – 2384

WChess 1.06 - 2338

WildCat 8 – 2628

Winchess

Wing 2.0a - 2108

WJChess 1.64 - 2137

Woodpecker 2.0

WSpeirs Chess

Xpdnt - 2482

Yace 0.99.87 – 2484

Zarkov 2.6

Zarkov 4.6

Zarkov 5.0

Zappa Mexico II – 2978

ZCT – 2202

Zeta Dva - 1969

Zeus 1.27 – 2306

Ziggurat 0.22 – 1789

Ziggy 0.7

Zochova 0.1

Zoe

Zurichess – 2441