Chess960 Chaos

Over on Chess960 Jungle, in a post titled Tricky Tricky Chess960, HarryO investigated a start position that I encountered in A Chess960 Catastrophe. The position, SP941 RKRBNQBN, was the start of a game at Mainz 2005, where GM Bacrot was completely lost against GM Aronian after four moves. HarryO concluded, '[Bacrot] stumbled on what I think could be amongst a few very very tricky SP's for Black to play and even worse it was against Aronian!' and 'There will be a very small number of SP's where Black's first move may have to be memorized or at least the tactical motifs will have to be memorized.'

Critics of chess960 like to say that there are some positions where the odds are stacked against Black at the beginning of the game and present this as a reason for not considering Fischer's greatest invention. Since these critics never give examples with analysis, unwitting readers might assume that they are right. Is SP941 such a position? I decided to take a closer look, subjecting it to engine analysis.

I'm not a big fan of using engines to analyze the early opening, where the best moves are often based on positional ideas like development and the center, rather than tactics. Engines also know nothing about piece harmony and coordination, a central concern in chess960 where the pieces are usually not as well coordinated as in the traditional start position, SP518 RNBQKBNR. In the case of SP941, where strong tactical motifs are present at the beginning of the game, an engine can help to cut through the tangle.

The first diagram shows the Aronian - Bacrot game after Aronian's first move. The most striking feature of the position is the RKR sitting in the corner. Castling is not going to be easy in this game and castling O-O is highly unlikely. The second feature is the weakness of the b- & d-Pawns. This was the problem that Bacrot underestimated.

To analyze the position, I used a normal engine that has no specific knowledge of chess960, i.e. without knowledge of the castling rules. Since castling does not play a role in the early moves, this is not a big disadvantage. The engine is the strongest I have, analyzing the early opening to >20-ply in only a few minutes, a feat that my chess960 engines can't do. After running the engine against the position with 1.e4, I looked at the top four moves it suggested: 1...f5, 1...f6, 1...e5, and 1...c5.

The first candidate move, 1...f5 leads to the early development of the Black Queen after 2.exf5 Qxf5. Now White can attack the Queen immediately with 3.Ng3, when 3...Qa5 calls to mind the Scandinavian Defense in SP518. Not all players are comfortable with an early deployment of the Queen and, while it looks safe on a5, its exposed position will certainly become a factor sooner or later.

Like 1...f5, the second candidate, 1...f6, opens the diagonal for the Bg8, but does little for the center. White can play an immediate 2.Bg4, hitting the weak d-Pawn, when Black responds 2...e6. This line of play looks passive and might not appeal to players who are looking for more than solidity in the opening.

The third candidate, 1...e5, was Bacrot's choice. It certainly looks natural. It uses a strategy of symmetry, which is often a good strategy for Black in the early moves of a chess960 game, and it opens diagonals for a Bishop and the Queen. The engine favors Aronian's move 2.Nd3 over all others, then suggests 2...f6 and 2...Ng6 for Black. Bacrot chose 2...Ng6, when Aronian answered 3.f4, also the heavy favorite for the engine. The two-fisted threat is 4.Nc5 & 5.Qb5, winning immediately. Instead of Bacrot's 3...Bf6, which overlooked the threat, the engine suggests 3...c5.

After the similar 2...f6 3.f4 c5, shown in the second diagram above, Black's position looks chaotic. The three Black Pawn moves aren't harmonized into any obvious plan and the e-Pawn is hanging. Although Black can recover it, the variations I looked at were all equally chaotic. It would take more analysis to determine if there is anything more to Black's game than parrying White's threats, but I stopped there.

The fourth candidate move, 1...c5 (the SP941 Sicilian?), also leads to chaotic looking positions. Its first merit is to interfere with White's Nc5, and by opening the file for a lift of the c-Rook and a diagonal for the dark squared Bishop, it heads for a fast ...O-O-O. HarryO advises to forget about it, but I think it's worth a try.

If I were faced with the position after 1.e4, I would probably play 1...e5, because I like advancing in the center. Would I see the idea with 4.Nc5 & 5.Qb5? If one of the world's top grandmasters missed it, what are the chances for us grandpatzers?