Stefan Pohl Computer Chess

private website for chessengine-tests


The Drawkiller Openings Project - the future of Computerchess


Idea: Stefan Pohl, basic-work: Stefan Pohl and Hauke Lutz, development and testing: Stefan Pohl



Download the Drawkiller-openings here


Download the testgames (Drawkiller, SALC, FEOBOS Noomen) here



The Drawkiller openings are based on the main ideas of my SALC openings, which were combined with a very good idea of Hauke Lutz: Very short openings-lines, which only contain pawn-moves.

The Drawkiller openings are not for playing vs. other books – all engines must use the Drawkiller openings in a tournament or testrun!


The original SALC openings were filtered out of human chess-games (filtered out of the BigDatabase).

SALC means "S"hort "A"nd "L"ong "C"astling: white and black castling to opposite sides (if white played 0-0, black played 0-0-0. If white played 0-0-0, black played 0-0)), both queens still on board. No double games. When using SALC-openings, the chance for attacks towards the opponent king is much higher than using normal opening-books. Because of this, computerchess using SALC openings, will bring more action and fun to watch (and a measureable lower number of draws), because the faster the computers get, the higher the quality of computerchess get and the higher the draw-rate in engine-engine-matches the computerchess is in danger to die the "draw-death" in the near future. So, using SALC openings will give computerchess a future beyond playing only draws or using strange and incorrect gambit-openings for a lower draw-rate!

The SALC-openings were a huge success. The draw-rates in the testruns were lowered from 63%-64% (using standard openings) to around 48% without pushing the scores of asmFish and Komodo closer to 50%. For more information please checkout the Readme-file in the SALC V5.02 folder, which you can download on my website, too.


The problem of filtering SALC opening-lines out of a database of human games is, that those SALC-positions are rare. In order to get a huge number of SALC-positions, it was necessary to make the opening-lines quite long (8 moves for the small 500 openings-set and 10 moves for the big 25000 openings-set and opening-book). And with 10 human moves played, the opening is done and the middlegame is starting already.


The idea of the new Drawkiller openings is, not to finish the opening in the opening-book, but to let the engines play their own opening-moves. This is especially important, when testing the new neural-net based engines (LC Zero for example), which are playing very strong and creative in the opening.


How can this be done?


Some months ago, Hauke Lutz had the great idea, to build some openings-sets, which contain pawn moves only (4 pawn-plies, 8 pawn-plies), so the engines had to move all other pieces in the openings by themselves. These pawn-plies files do not contain strange pawn-moves (a4,b4,g4,h4), which would lead to really strange positions on the chessboard.


Of course, these pawn-move opening lines can not be SALC-positions, because all other pieces stay on their starting position. But then, I had the idea, that it is possible to combine these pawn-move openings with some moves, which


a) move queen, bishop and knight „out of the way“, then


b) (move the white king to a1, the a1-rook to d1 and the queen to e1) or (move the white king to h1, the h1-rook to e1). And the same for black, moving the king to the opposite side of the board (a8 or h8), so, when the white king is on a1, the black king is on h8, when the white king is on h1, the black king is on a8. That creates „SALC“-like starting-positions, with both queens never on the same line (one queen is on e-line, one queen stays on d-line – that prevents early queen-captures, when the d-line is opened! - I took this idea from my SALC-half-closed positions, which measureable lowered the draw-rate (around -5%) compared to not-half-closed SALC-positions).


c) move bishop and knight back to their normal starting position


And, when this is done, the pawn moves of Hauke Lutz are played.


These are the two move-sequences, which create the „SALC“-like king- and rook-positions on the chessboard:


1. e3 d6 2. Nh3 Na6 3. Bc4 Bf5 4. Ke2 Qd7 5. Na3 Qe6 6. Nb1 Kd7 7. Re1 Rd8 8. Kf1 Kc8 9. Kg1 Kb8 10. Kh1 Ka8 11. Ng1 Nb8 12. Bf1 Qd7 13. Nh3 Qe8 14. Ng1 Bc8

1. d3 e6 2. Na3 Nh6 3. Bf4 Bc5 4. Qd2 Qf6 5. Qe3 Na6 6. Kd2 Nb8 7. Rd1 Ke7 8. Kc1 Re8 9. Kb1 Kf8 10. Ka1 Kg8 11. Qd2 Kh8 12. Qe1 Qd8 13. Nb1 Ng8 14. Bc1 Bf8


As you can see, only one pawn-move (1.e3/d3 1...e6/d6) is needed, to open a way for bishop and queen for each color. This pawn-moves were filtered out of the pawn-move openings by Hauke Lutz – then the pawn-move opening-lines could be linked together with the move-sequences from above, without generating impossible (illegal) move-sequences. The result are „SALC“-like openings (=kings on different sides of the board), without any piece, except pawns, the king and one rook and one of the two queens, moved away from their normal starting positions.


Here an example of a „complete“ artificial SALC opening-line out of the drawkiller_tournament.pgn file:


1. e3 d6 2. Nh3 Na6 3. Bc4 Bf5 4. Ke2 Qd7 5. Na3 Qe6 6. Nb1 Kd7 7. Re1 Rd8 8. Kf1 Kc8 9. Kg1 Kb8 10. Kh1 Ka8 11. Ng1 Nb8 12. Bf1 Qd7 13. Nh3 Qe8 14. Ng1 Bc8 15. h3 c6 16. e4 f6 17. d4 e5



(the line is 17 moves deep, but only 3 pawn moves were made (and the kings „traveled“ to the edge of the board), so for engine-play, this opening-line is only 3 moves deep and the engines have to play the whole opening by themselves and have to move all non-pawns-pieces from the baseline).


These Drawkiller openings combine the advantages of very short opening-lines and the much more spectacular and much less drawish chess, my SALC-idea brings to computerchess.


Important: Mention, that the Drawkiller openings contain only normal chess-moves, each line is starting from the normal starting-position of classical chess. Drawkiller openings are not any kind of a chess-variant, like Shuffle-Chess or Chess960 or something like that! Because of this, it was possible to build opening-books for the ChessGUIs (Fritz, Arena, Shredder) out of the Drawkiller openings, which can be used for engine-tournaments in that GUIs. And each chess-engine on the planet can play chess, with using Drawkiller openings, because they are normal, classical chess!!!



Test results:


(asmFish 170426 vs. Komodo 10.4, 5'+3'' time-control, singlecore, no ponder, no endgame-bases, LittleBlitzerGUI, 1000 games each testrun(!) except Noomen Gambit-lines (only 246 positions, so 492 games were played) and Noomen TCEC Superfinal (only 100 positions, so 200 games were played))


Stockfish Framework standard 8 move openings: Score 60.3% – 39.7%, draws: 63.4%

FEOBOS v20 contempt 5 top 500 openings: Score 58.7% - 41.3%, draws: 64.1%

HERT 500 set: Score: 60.6% - 39.4%, draws: 60.4%

Noomen Gambit-Lines: Score 59.1% - 40.9%, draws: 59.3%

4 GM-moves short book: Score 60.5% - 39.5%, draws: 57.1%

Noomen TCEC Superfinal (Season 9+10): Score: 62.5% - 37.5%, draws: 50.0%

SALC V5 half-closed: Score 61.6% - 38.4%, draws: 49.2%

SALC V5 full-closed 500 positions: Score 66.5% - 33.5%, draws: 47.7%




Drawkiller (Big set): Score 63.8% - 36.2%, draws: 39.5%


Drawkiller (Normal set): Score: 65.3% - 34.7%, draws: 33.5%

Drawkiller (Tournament set): Score: 65.3% - 34.7%, draws: 33.5%


(no mistake by me: the results of the normal-set and the tournament-set were exactly the same after 1000 played games in my testruns)

As you can see, the Drawkiller openings are not just an improvement over my SALC openings, they are a breakthrough into another dimension! Never before any openings-set gave such low draw-rates without crunching the scores of the engines towards 50%, but instead pushing the scores away from 50%. The Drawkiller Normal- and Tournament sets nearly halve the draw-rate, compared to FEOBOS or the Stockfish Framework 8-move openings. I would never have expected, that this was possible – the Drawkiller project is really a breakthrough into another dimension. And the Drawkiller project kills the draw-death of computerchess for the next decades – mention a TCEC-tournament with nearly halved draw-rates... how awesome would be that?!?




Enjoy Drawkiller-Chess


As you can see in the testing results, the drawrate of the big Drawkiller openings is a little bit higher, than the drawrate of the tournament-files and the normal-files. So, I recommend, to use always the smallest Drawkiller openings set/book, which is possible for your engine tournament or testrun. That will give the best results. For the most tournaments and testruns, the normal-files (13318 different endpositions) or the tournament-files (6848 different endpositions) should be big enough. Use the Big-files only for very big tournaments with many, many games - I would recommend the big-files only for engine-developers, who want to measure small Elo-gains of single patches.


Each folder with Drawkiller openings contain the raw-data, too. The raw-data contains the unfiltered, unchecked and unmixed pgn-files. Do not use these files for engine-play, they contain very bad endpositions for white or black. The raw-data was included, to make it possible, to filter that raw-data in the future again (with stronger engines or faster machines), so the Drawkiller openings can be rebuilt in the future!



The Drawkiller openings were filtered out of this raw-data with Komodo 11.2.2. Komodo checked all endpositions (using pgnscanner-tool), running on a i7-6700HQ 2.6GHz Notebook (Skylake CPU) with all 4 cores and 2048 Hash, Contempt=0.


The Komodo evaluation had to be in that interval for the big-files and the normal-files, otherwise, the position was deleted:

eval: [-0.49;-0.10] or [+0.10;+0.49]


For the tournament-files, the Komodo evaluation had to be in an even smaller interval:

eval: [-0.39;-0.20] or [+0.20;+0.39]



You can see, that the eval-intervals are quite small. No endposition of any Drawkiller opening gives a huge advantage to white or black!


Thinking-time for each endposition was:

Normal/Tournament set: 45''

Big set: 30''



Copyright (C) 2018 by Stefan Pohl, except the used pawn-plies sets (4pp and 8pp (6pp was built by Stefan Pohl out of the 4pp-set, too)): (C) Hauke Lutz