Stockfish, Houdini Battle For Computer Chess Championship; Komodo vs Lc0 For 3rd
Stockfish was the runaway winner of stage two in the Computer Chess Championship, and will face Houdini in the finals.

Stockfish, Houdini Battle For Computer Chess Championship; Komodo vs Lc0 For 3rd

| 90 | News

Proving that it's still the biggest fish in the sea of computer chess, the Stockfish engine cruised to the top spot in the Computer Chess Championship, scoring an astounding 51/70 against the world's top chess engines in stage two of the rapid event CCCC 1. 

Stockfish will play in the finals against Houdini, which finished second in stage two and escaped continuous pressure from Komodo and Lc0 ("Leela"), who rounded out the top four.

cccc 1 stage 2 standings computer chess

CCCC 1: stage two results. Stockfish and Houdini are through to the finals. 

Stockfish and Houdini will play a 200-game finals to determine the winner of CCCC 1: Rapid Rumble, which is already in progress at

Komodo and Lc0 will play a third-place match (30 games) immediately following the finals.

The engines Ethereal and Fire finished in fifth and sixth place in the eight-engine stage two.

All six of the top engines from stage two will qualify for the CCCC 1 bonus rounds, where the engines will play five odds chess positions that are likely to be popular with the fans in the chat at and

CCCC 1 finals:

The Stockfish-Houdini finals will be played under the same conditions as the rest of the CCCC, except that the openings will be the top 100 most-played lines by human members. The first six plies of the top 100 lines will be played by each engine, and they will reverse colors for every position.

In an improvement for the finals, the reverse games will begin immediately after the original games. 

You can download a PGN of the openings in order of play here.

The finals are expected to last about one week from their start on Tuesday, Sept. 25. 

Stage two results:

Stockfish's dominance was the story of stage two, as it did not lose a game and racked up huge winning margins against most of the other engines in the group. Lc0 put up the toughest resistance, losing its mini-match vs Stockfish by the thinnest of margins, 4.5 to 5.5.

cccc 1 stage 2 crosstable

Stage two crosstable. Click on the image for a larger version. 

The machine-learning engine Lc0 was not able to capitalize on opportunities in the rest of the tournament, however, dropping two games in seemingly inexplicable fashion to last-ranked Andscacs.

Houdini did not fare well against its finals opponent in stage two, losing its mini-match to Stockfish 2.5 to 7.5 with zero wins. Houdini fans are hopeful the engine can find some winning magic in the finals, but make no illusions about it: Stockfish is an overwhelmingly heavy favorite to take first place in CCCC 1.

The third-place match between Komodo and Lc0 looks to be more closely fought, as Lc0 edged Komodo 5.5-4.5 in the stage two mini-match with two nice wins.

You can download all of the stage two games here:

Download full PGN CCCC 1: Rapid Rumble | Stage 2

Stage one games can be found in the previous news report.

Selected stage two games:

Lc0 vs Komodo:

Lc0 grinds out a win vs Komodo with the strange opening (selected by 2. Qd3. Lc0 shows it has the patience to beat a top-tier traditional engine in a drawn-out, positional game.

Houdini vs Andscacs:

In what looked like a slow positional buildup, Houdini brilliantly and suddenly transitioned to a brutal kingside attack, then gave everyone a lesson on winning king-and-pawn endgames.

Booot vs Komodo:

Komodo shows its class with a sharp exchange sacrifice in the early middlegame that dooms Booot's king.

Lc0 vs Stockfish:

We've selected a win for all the other top-four engines, but Stockfish's dominating performance at 51/70 leaves it with nothing to prove. Instead, check out this beautiful draw Stockfish saved against Lc0 that had human chess players shaking their heads in disbelief.

IM Daniel Rensch analyzes this game in what was a deep, personal journey in his knowledge of pawn endgames. Watch the video lesson below.

Third-place match:

Lc0's devoted fan base will have two more chances to see Leela play in CCCC 1—first in the third-place match vs Komodo and then in the bonus games rounds.

Komodo and Lc0 will play 30 games with 15 random openings selected from the same 100-opening book used in the finals. The match will begin immediately after a winner is crowned between Stockfish and Houdini and is expected to last about one day.

Bonus games:

After the finals and the third-place match, computer chess fans can relax and enjoy some bonus rounds of odds chess positions. These crazy games might not settle who is best at traditional chess, but they are sure to provide fireworks on the chessboard.

The top six engines from stage two will play a 2x-round-robin tournament with five different positions for a total of 150 games. Each engine will play every other engine one time as White and one time as Black in each position.

The bonus rounds are expected to last about four days of non-stop, odds-chess action.

Details on the positions are below.

Bonus games participants—top 6 engines from CCCC 1:

  • Stockfish
  • Houdini
  • Lc0
  • Komodo
  • Ethereal
  • Fire

Bonus position 1: Knightmare! White starts with only knights for pieces while Black starts with normal piece set minus the knights.

Stockfish 9 starting eval: -4.88

Who knows what will happen in this crazy position? Stockfish claims it's an easy win for Black, but are we sure we won't see some draws or even wins for White? Stay tuned. 

Bonus position 2: White missing f2 pawn.

Stockfish 9 starting eval: -1.00

The stronger engines might be able to save these games for draws. Do not expect a clean sweep for Black. Regardless, it will be exciting chess.

Bonus position 3: Replace rooks with queens.

Stockfish 9 starting eval: +0.35

Rooks are boring because all rook endings are drawn. Let's see what happens when they start with queens instead.

Bonus position 4: Sideways chess! (minus the rooks)

Stockfish 9 starting eval: +1.49

Does going first give White a winning edge in this crazy position? Komodo disagrees already and says Black is OK...but is it?

Bonus position 5: Moving on up! White starts up one rank. White can't castle but Black can.

Stockfish 9 starting eval: +1.18

This one is a lot of fun. Does an extra rank of space equal a win for White?

CCC 2: Blitz Battle:

After all the festivities of CCCC 1 come to a close, get ready for the next event, which is called CCC 2: Blitz Battle. has officially dropped a "C" from the title, but will add the latest versions of each engine for the second event.

That's right, Leela fans, you will get to see all the progress Lc0 has made with its new networks in event two. will also make some technical adjustments to provide better competitive balance that will be announced in the CCC 2 rules later to come. The time control will be blitz chess (likely five minutes + two seconds increment, pending testing).

You can follow all the Computer Chess Championship action on with the new and groundbreaking user interface, or head to to enjoy some AI-composed music while watching the games stream.

Previous Computer Chess Championship news:

More from Pete
Aronian, Artemiev Advance In Thrilling Speed Chess Championship Doubleheader

Aronian, Artemiev Advance In Thrilling Speed Chess Championship Doubleheader

Stockfish Wins Computer Chess Championship As Neural Networks Play Catch-Up

Stockfish Wins Computer Chess Championship As Neural Networks Play Catch-Up