2023/09/01 DPA: "Alignment and Tempo"
"Endgame. Why did it have to be an endgame?"
"Rook and Pawn; very dangerous...you go first!"
[With a hat tip to "Raiders of the Lost Ark" scene with Indy and Salah
https://www.youtube.com/watch?v=WiXgXIfy-sw
1. ... Rb4 2. Rd4 Rxd4+ 3. Kxd4 was the first thing that came to mind. But in my mind's eye, I still had the King on e4 so, even though White will promote first [he is 4 moves away whereas Black is 5], Black will skewer the White King and win the Queen.
"It's Friday: it can't be this easy."
So I looked more carefully and realized my error. So 1. ... Rb4 is out. But don't discard the skewer idea yet.
Black wants to trade Rooks [to eliminate counterplay] AND wants the White King on the a8-h1 diagonal so the skewer can work.
Well, White's Rook is on that diagonal so if the trade can be made to happen there, Black will achieve his goal.
1. ... Re1+ 2. Kd3 [or 2. Kd4; it doesn't matter. The important thing is that White's King cannot attack the Rook - he is one square too far.]
2. ... Rd1+ 3. Kc4 [or 3. Ke4; it doesn't matter] Rxd5 4. Kxd5
If both sides simply push their respective pawns, the skewer scenario occurs and Black wins. So White throws in a last-ditch effort by first moving off of the a8-h1 diagonal with 5. Kd4 h5 and then attempting to get to h1 with 6. Ke3. If Black ignores this and keeps pushing, the White King will reach the h1 corner and will be impossible to dislodge.
So Black must first prevent this with 6. ... Kg3. The puzzle continued with both sides promoting and, since Black promoted first and guards White's promotion square, he wins.
The more interesting line was 7. Ke2, still trying to get to h1. In this case, Black must not play the "obvious" 7. ... Kg2 because now his King is on the dangerous diagonal. This will catch a lot of people because we're taught to use our King to box out the enemy King, so 7. ... Kg2 is a natural reaction if one doesn't stop to look more closely.
Instead, he should play 7. ... h3 8. Kf1 h2 and promotion cannot be stopped.
I'm not sure why this line wasn't chosen as it offers one more way for the solver to err. I guess they decided to stop at 2 traps [1. ... Rb4+ and 5. ... h4].
This puzzle demonstrates how a single tempo and the configuration of the pieces when the pawn pushes begin can make the difference between winning and losing [or drawing]. In the opening and middlegame, one can usually recover from one misstep; in the endgame, there's no time.