2025/03/08 DPA: "ESSAS [Empty Square Sac Avoidance Syndrome]"

White to move:

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White is down in material [2 Rooks for a Queen + Bishop].

1. Nxe4 Qxe4  2. Rc8+ Bf8  3. R[either]xf8#; or 2. ... Bd8  3. Rxd8#.

That wins a Bishop but now it's 2 Rooks v Queen, which is only a one point advantage.  Add to that this is Saturday and this solution is too simple for a Saturday.

1. Nd5 threatens 2. Nxe7+ Royal Fork.

• 1. ... exd5  2. Rc8+, etc
• 1. ... Bxd5  2. Rc8+, etc
• 1. ... Bd8/f8 [to block 2. Rc8+ before it happens]  2. Ne7+ Bxe7  3. Rc8+, etc.
• 1. ... Qe8  2. Nxe7+ Qxe7  3. Rc8+, etc.
  • 2. ... Kh8  3. Rc8, pinning the Queen

The only check available to Black is 1. ... Qxg2+ but that just loses the Queen.

This looks like the solution.

That was it.  The only wrinkle was Black chose 1. ... Bf6 but it didn't change the Solver's attack idea of 2. Ne7+.

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The keys were:

• Recognizing that the obvious 1. Nxe4 was insufficient [both from a material standpoint and a day of the week standpoint [too simple for a Saturday]
• Seeing the potential back rank checkmate and therefore, the Knight had to get out of the way of the c Rook
• But the Knight move had to threaten something valuable enough that forced Black to react rather than just playing 1. ... h6 to avoid a back rank checkmate
• 1. Nd5 was the only move that fit the bill:  a threatened Bishop capture with a Royal Fork
• Calculating that any capture of the Knight led to 2. Rc8+ or any Queen move to protect the Bishop led to Nxe7+ and then 3. Rc8+
• The solution chose 1. ... Bf6 to escape capture and block the f file.  Now the Solver had to find the second Knight sac offer of 2. Ne7+, ignoring the tempting 2. Rc8 and sticking to the original plan:  if Black doesn't capture, we win the Queen for a Knight; if Black does capture, it leads to 3. Rc8+ and checkmate

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I coined the term ESSAS [Empty Square Sac Avoidance Syndrome]:  it's the situation where one must sacrifice on an empty square, meaning we offer up our piece for no material in return.  I noticed that it feels psychologically more difficult than a normal sac where we at least get some material in return [even just a pawn].

This puzzle was difficult because it contained not one but two sacs that are subject to ESSAS:  1. Nd5 and 2. Ne7.  It somehow feels wrong or foolish to sac on an empty square but it's absolutely an option and in this case, was the only solution.

This was ESSAS writ large because we had to do it twice.

In the Tata Steel broadcast, commentator Jon Sargent mentioned this idea when Jorden Van Foreest played just such a move [I think it coincidentally happened to also be Nd5 as White].

Nice puzzle, @BryanCFB!