Komodo and Dragon by Komodo Chess (also known as DragonorKomodo Dragon) are UCIchess engines developed by Komodo Chess,[1] which is a part of Chess.com.[2] The engines were originally authored by Don Dailey and GMLarry Kaufman. Dragon is a commercial chess engine, but Komodo is free for non-commercial use.[3] Dragon is consistently ranked near the top of most major chess engine rating lists, along with Stockfish and Leela Chess Zero.[4][5][6][7][8]
Komodo was derived from Don Dailey's former engine Doch in January 2010.[9] The first multiprocessor version of Komodo was released in June 2013 as Komodo 5.1 MP.[10] This version was a major rewrite and a port of Komodo to C++11. A single-processor version of Komodo (which won the CCT15 tournament in February earlier that year) was released as a stand-alone product shortly before the 5.1 MP release. This version, named Komodo CCT, was still based on the older C code, and was approximately 30 Elo stronger than the 5.1 MP version, as the latter was still undergoing massive code-cleanup work.[11]
With the release of Komodo 6 on October 4, 2013, Don Dailey announced that he was suffering from an acute form of leukaemia, and would no longer contribute to the future development of Komodo.[12] On October 8, Don made an announcement on the Talkchess forum that Mark Lefler would be joining the Komodo team and would continue its development.[13]
Komodo TCEC was released on December 4, 2013. This was the same version that had won TCEC Season 5, and was the last with input from Don Dailey, to whom it was dedicated.[14] Komodo 7 was released on May 21, 2014, adding Syzygy tablebase support.[15]
On May 24, 2018, Chess.com announced that it has acquired Komodo and that the Komodo team have joined Chess.com.[2] The Komodo team is now called Komodo Chess.[1]
On November 9, 2020, Komodo Chess released Dragon by Komodo Chess 1.0, which features the use of efficiently updatable neural networks in its evaluation function. Dragon is derived from Komodo in the same way that Komodo was derived from Doch.[18][19] Dragon is also called Komodo Dragon in certain tournaments such as the Top Chess Engine Championship and the World Computer Chess Championship (WCCC) but not in the Chess.com Computer Chess Championship (CCC). A Chess.com staff member named Dmitry Pervov joined the Dragon development team to write the NNUE code for Dragon, and Dietrich Kappe joined the Dragon development team to help Larry Kaufman and Mark Lefter train Dragon's neural networks.[20]
The latest version, Dragon 3.3, was released on October 4, 2023.[21] On March 17, 2023, Larry Kaufman announced that he and Mark Lefter have stepped down from Dragon development and from ownership of Komodo Chess, and that Chess.com have taken full control of Komodo Chess. As of March 17, 2023, Dietrich Kappe is the only person responsible for the development of Dragon, but Chess.com are looking for more programmers to help with Dragon development.[22]
Komodo has played in the ICT 2010 in Leiden, and further in the CCT12 and CCT14. Komodo had its first tournament success in 1999, when it won the CCT15 with a score of 6½/7.[23] Komodo won both the World Computer Chess Championship[24] and World Computer Software Championship[25] in 2016. Komodo once again won the World Computer Chess Championship[26] and World Blitz[27] in 2017.
InTCEC competition, Komodo was historically one of the strongest engines. In Season 4, it lost only eight out of its 53 games and managed to reach Stage 4 (Quarterfinals), against very strong competition which were running on eight cores (Komodo was running on a single processor).[28] The next season, Komodo won the superfinal against Stockfish. The two engines jockeyed for the championship over the next few seasons: Stockfish won in Season 6, while Komodo won Seasons 7 and 8. Komodo failed to make the superfinal in Season 9, losing out to Houdini; but after Houdini was later disqualified for containing code plagiarized from Stockfish,[29][30][31] Komodo was promoted to the runner-up. Komodo retrospectively won Season 10 in the same way. Starting from Season 11 however, Stockfish improved at a rate that left its rivals behind, crushing Komodo in Season 12 and 13. The advent of the neural network engine Leela Chess Zero meant Komodo has largely failed to qualify for the superfinal since, with a single exception in Season 22, when it lost to Stockfish. Although Komodo has not qualified for the superfinal, it has cemented itself as the third-strongest engine in the competition, finishing in that position for five of the last six seasons.
