patzer2: Missed on today's Sunday (28.?) puzzle with 28. Re4, which gives Black equality after 28...Ng6 = (0.00 @ 37 ply, Stockfish 10).I looked at 28. Rxg7!! Kxg7 29. Re4 Rf5 and immediately gave up on the variation because of the threat 30...Qa1+ 31. kh2 Nf3+ -+ winning the White Queen with a discovered attack with check.
What I missed is the pin 30. Bd4!, which eliminates the discovered attack threat and proves the exchange sham sacrifice 28. Rxg7!! sound by giving White a won position against the exposed Black King.
For my two Grandsons, who are active in scholastic chess, I'd point out the reflex material grab 33. Rxe4? is a mistake which loses to the Queen fork 33...Qf4+ -+ (-1.73 @ 33 ply, Stockfish 10).
Another instructive follow-up combination is 38. Nd5+! Rxd5 39. Qg6 +- (mate-in-12, Stockfish 10) which forces Black's resignation due to the threat 39...Ke7 40. Re4+ Kd7 41. Qxe8+ Kc7 42. Re7+ Kd6 43. Qd7+ Kc5 44. Qc8+ Kb4 45. Qxc1 +- (mate-in-six, Stockfish 10).
P.S.: So where did Black go wrong?
The computer indicates the losing move was 26...Kh8?, allowing 27. Qxc5 +- (+1.74 @ 30 ply, Stockfish 10). Instead, snatching the pawn with 26...Qxb2 27. Qxc5 Ng6 28. Ne4 Re5 ± (+0.87 @ 32 ply, Stockfish 10) appears to give Black reasonably good drawing chances.
A few moves earlier, I didn't like 23...Nd7?! allowing 24. Rg5 ⩲ (+0.55 @ 30 ply, Stockfish 10) because it appears too passive and seems to give White a strong attacking initiative.
Instead, I prefer the more active defense 23...Rae8 = (0.00 @ 33 ply, Stockfish 10) because the pawn grab 24. Qxd6? isn't possible due to 24...Rxe3 -+ winning a piece.
Kibitzing
sac: 28.Rxg7
