Final draw rate was 46.4%.
Game termination
The three most common game termination causes were:
48.2% - TCEC win rule
19.6% - 3-fold repetition
16.1% - TB position
The number of 3-fold repetitions was unusually high, the engines preferred repeating over lowering the eval to 0 and adjudication. There were 3 crashes, Pedone came close to being disqualified with two crashes.
Moves per game
Median= 55
Average= 65
The distribution has unusual peaks, in particular there were 6 games (10.7%) with more than 130 moves. This was mainly because some engines had problems evaluating drawn positions.
Time per game (hours)
Median= 1:13
Average= 1:13
Openings
There were 2-move book openings in this stage chosen by Cato. The first letter of the ECO codes was distributed as follows:
For each round all four games had the same book sequence, and again in the reverse round. There were 7 book sequences, each repeated 8 times. For some sequences all the openings had similar codes (e.g. Sicillian or French). In others the engines had more freedom to choose (rounds 3 and 10 were either QGD or Indian defences, and one Benoni).
If we use the opening 'family name' (using format FAMILY_NAME: VARIANT....) the top 3 are:
Sicillian - 16 times
Caro-Kann - 8 times
French - 8 times
The engines had a lot of freedom to choose the opening variant. Only 18% of the game pairs repeated the same ECO code twice, and none repeated the same opening variant. In 7.1% of the game pairs the ECO first letter was not repeated twice.
Reverse pairs, wins
The 3 "biased" results all involve Toga, this says more about Toga's ability than the openings which were all very popular, short and unbiased.
Reverse pairs, same moves
Pairs of reverse games diverged very quickly, 60.7% of the pairs diverged immediately after book.
