I have only glimpsed at the games when they were live, this post is mostly from going quickly over the archives.
The situation after 6 rounds is as follows:
Stockfish, Houdini and Equinox will qualify for sure. My bet for the other three is Chiron, Hannibal and Nirvana. Nightmare is also a surprise contender with low rating. I don't think any of the others has any chance, including Junior which is having a bad tournament with too many crashes.
Junior recorded the quickest crash possible when it crashed as white before making a move against Stockfish. Some say it was too scared to play. And this was with reduced threads and hash to "improve stability".
Stockfish had two impressive wins against strong opponents, Hannibal and Nirvana. So far I am happy with its performance, no time trouble and a good attacking style. The real tests are still to come in the following stages.
In rounds 5 and 6 Crafty's evaluation was somehow inverted. It played as black and gave positive scores for black's advantage, contrary to the convention of TCEC. As a result the GUI could not adjudicate when white was winning since Crafty gave high negative scores. The games played on until a TB adjudication was possible. This was later fixed.
Nightmare - The Baron, round 4
Game on TCEC archive
The game was balanced from the start, with evaluation scores close to 0 from both engines. We join the action after move 24.
The Baron saw an opportunity to take the f2 pawn, but this allowed Nightmare to trap the black rook. After exchanging pawns on the queen side Nightmare created a passed pawn on the c file, backed by a rook.
The a pawn was next to go, Nightmare had two passed pawns backed by rooks. The trapped rook broke free but only to aid in the blocking of the white pawns.
White now used its queen to break the blockade preventing the white pawns advance to the 8th row.
What a beautiful position! White threatens to take the rook, and black cannot take the queen because it loses the rook.The game was over within a few moves.