Komodo Dragon 2.6.1 - Review

Updated: May 9

This time we will take a look at one of the TOP chess engines.

According to the Creators: a lot of improvements, some new features, development of a "human" style of play.

Is indeed the new Dragon By Komodo Chess worth interest, is the MCTS algorithm a useful alternative to engines using standard search functions?

I will try to answer these and other questions in this review.

Source image by ChessBase

By way of introduction, I'm pasting information from one of the Komodo Dragon GM Larry Kaufman, who unveiled the latest version of this engine in December 2021.

[December 20, 2021] We have released Dragon 2.6 at komodochess.com. Dragon uses NNUE (Neural Network Updated Efficiently) technology, originally developed for the game of shogi. Komodo has a great deal of chess knowledge in its evaluation. Training an NNUE network based on this evaluation was both an advantage and a challenge, requiring experimentation with architectures and data generation of billions of positions. The reinforcement learning phase for Dragon is in its infancy, but is already showing great promise.

Dragon 2.6 is a huge strength improvement over Dragon 2, roughly 70 elo at blitz on four threads and 83 elo on one, more than 100 elo in MCTS mode and for playing Fischerandom (chess960). It is a significant improvement over Dragon 2.5, about 18 elo on one thread blitz, about 25 elo in MCTS mode or playing chess960. The gains over Komodo 14.1, the last pre-dragon release (Nov 2020), are in the 250 to 350 Elo range depending on threads, mode, and game type, all at CCRL blitz time control (2' + 1"). The improvement over Dragon 2 is due to a larger, "smarter", and better-trained net, to deeper search due to search enhancements, and to parameter tuning. The improvement from Komodo to Dragon is due to the embedded neural network providing much more accurate evaluation and also in some sense gaining an extra ply or so of search by seeing some tactics that a normal eval can not see. Our testing also shows that Dragon is especially strong in Fischerandom (960) chess, which was confirmed when Dragon won the TCEC FRC 2021 championship, and again in our latest testing that shows Dragon 2.6 convincingly defeated Stockfish 14 in a 2000 game blitz Fischerandom match. Dragon also won the 2021 TCEC Swiss and Swiss2 championships (normal chess). We believe that Dragon will play in a more human-like style than standard Komodo since it relies on learning what actually works in games rather than just on pre-assigned values for eval terms.

The Skill levels have been replaced by Elo values, made much more human-like, and are now intended to correspond to human Fide ratings in Rapid chess, so for example an 1800 FIDE rated player should be closely matched with UCI Elo 1800 at 15' + 10". Also the MultiPV play of standard mode is dramatically improved from the initial dragon release, on top of the actual strength gain. Other features added since Komodo 13 include Armageddon mode, MCTS Optimism, Personalities, and Auto-Skill. Standard mode is usually the stronger mode objectively, while MCTS mode is usually better at setting problems for human opponents as it does not assume perfect defense, especially with more than a few seconds to consider, and is also stronger than standard mode when looking at several lines of play at once (MultiPV).

It sounds very interesting, doesn't it?

Table of Komodo Dragon engine specifications.

Before I get into specifics, a brief history of this chess engine.

Komodo Dragon (Dragon for short) is a commercial chess engine that is a direct successor to the Komodo engine.

Dragon has a long history and many different successes. It is a multiple-time Computer World Champion. Its development over the years is regular. Every few months the Developers release new updates and new versions of this engine.

Power of play.

Dragon is a very powerful chess engine with an established reputation, which usually occupies the top spots in chess engine ranking lists.

Source: CCRL

Attached for download is a match consisting of 100 games of Dragon against the Rebel 14.2 engine. Each engine had 1 CPU at its service and 1 minute per game; Fritz 18 GUI, Perfect 2021 opening book.

The result of the match shows the colossal difference in playing strength between top engine Dragon (over 3500 Elo) and very strong engine Rebel (about 3200 Elo).

Komodo Dragon 2.6.1 vs Rebel 14.2_100games.pgn
Download ZIP • 95KB

Out of 100 games:

  • Dragon won 81 and tied 19.

  • Rebel won 0 games and drew 19.

The image below shows one of the games in progress.

Style of play.

Dragon plays positional style chess by default. Of course, an engine that plays with a strength of about 3500 Elo will excel in positions that require a tactical approach. Undoubtedly, Dragon's style of play has not changed dramatically compared to its predecessor, and it still favors a more maneuverable game leading to an advantage rather than a frantic attack paid for by the sacrifice of pawns and pieces.

Invariably, the ability to select predefined personalities that allow the user to easily customize Dragon's playing style for their own needs is a delight.

Using three examples from my practice, I will show how Dragon can play.

For comparison, I'll contrast Dragon's suggestions with those of the super-powerful Stockfish engine.

The following examples are from my correspondence games.

23... Ne3 ! - this impressive and - as it turned out later from the course of the game - effective move is suggested by Dragon in an extremely dynamic and complicated position.

Stockfish engine suggests after a few minutes of consideration a different continuation line - probably just as strong 23... Qg6, though probably less interesting.

Position evaluation.

Great move with the pawn to the h4 field. Dragon is the engine that saw in perspective that 15.h4 leads to a big advantage for white.

The game ended with a victory for white, who through the move 15.h4 led to a situation where black could do nothing effectively.

Analysis using the Monte-Carlo Tree Search (MCTS) algorithm.

Another example of a position that is very difficult for chess engines, in which most engines cannot see the line that causes the most problems for the opponent.

Dragon rightly points to the black Queen's move 33.... Qd4 after which white would have to play very precisely to save the draw. In the correspondence game, my opponent didn't respond precisely which in this position led to his surrendering the game after only 5 more moves!

I would like to point out that in a not easy position Dragon using only 1 CPU and the MCTS algorithm did a great job of simultaneously giving the 3 strongest continuation lines including 33... Qd4 which causes most potential problems for the opponent.

Dragon engine parameters.

Dragon gives the user many different parameters at his disposal. Compared to other chess engines the number of parameters to change is one of the most numerous. The parameters can affect the style and strength of play and many others including training support for the chess player.

For ambitious players, coaches and professionals - the rich possibilities of changing the Dragon engine parameters can be very helpful in learning, training, analysis including heavy analysis of correspondence games, looking for novelties and ideas and checking for errors in chess games.

In the applications of a correspondence chess player, customizing the Dragon engine to your needs can be one of the most effective weapons in playing against other opponents.

How to use the parameters, what size hash to choose, and more are included in the description file that Komodo Chess provides.

Training with Komodo Dragon.

1. Personalities

The Dragon engine has various capabilities that are useful during training.

One of them, as I mentioned above in the text, are - personalities - different styles that Dragon can play according to.

2. Dragon Elo strength setting.

Ability to set Dragon strength from 0 to 3500 Elo.

3. Auto Skill

The Auto Skill feature makes Dragon automatically adjust its internal Elo level when you play against it. When you set your Elo ranking, with Auto Skill enabled, it adjusts your level based on your game position rating, giving you a better chance of winning if you fall behind. If you are winning, Auto Skill raises your level. If you are losing, it lowers your level. This is designed to motivate the student and increase the chances of winning.

4. Armageddon.

Dragon can play Armageddon, where one side must win. So Dragon will treat a possible draw in the game as its defeat. Enabling Armageddon during training can result in some very interesting chess games from that chess engine.

5. Dragon & chess training software.

If you want to use one of the best chess training programs in combination with the Dragon engine, then you should check out the proposal of ChessBase company, which sells the Komodo Dragon engine perfectly integrated with its GUI.

Of course, Dragon works very well with other popular chess training GUIs such as Lucas Chess, Fritz, etc., however, you should know that you then have to manually install the Dragon engine using those programs.

Dragon and various GUIs (Graphical User Interface).

Dragon works properly with all GUIs that allow the chess engine to be used via the UCI protocol.

In practice all popular GUIs like Shredder Classic, Hiarcs Chess Explorer, Fritz, Arena, Banksia, Tarrasch and others support the Komodo Dragon engine.

Dragon availability for different operating systems.

Komodo Dragon is one of the few engines available for all popular operating systems. Linux, Mac and Windows - you can use Dragon on these systems.

The wide availability of Dragon is very good news for the growing number of chess players using different operating systems. They can use Dragon on their favorite system such as a Linux or modern Mac with a fast M1 processor.


Komodo Dragon is an unusual chess engine. Created by professionals for professionals and ambitious chess players.

  • Dragon "sees" much more than almost all other chess engines although its search depth is usually less.

  • It uses very advanced algorithms and methods for searching moves including NNUE (Efficiently Updatable Neural Networks) and MCTS (Monte-Carlo Tree Search).

  • Analyzes by providing realistic and unbiased evaluation of positions, including the most complex ones arising in correspondence games.

  • It offers useful and rare possibilities to support chess training.

  • With the option to change parameters, Dragon can be an extremely powerful and surprising partner during games and analysis, and exploration of novelties openings and ideas.

  • It has a very well implemented MCTS algorithm that allows you to analyze the position visualized by multiple lines - at the same time without any additional load on computer resources.

Komodo Dragon 2.6.1 score


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