patzer2: In today's Saturday (19...?) puzzle, the weak position of the White King begs for a demolition sacrifice leading to mate.Stockfish 10 indicates three combination (i.e. sham) sacrifices (19...Rxe4, 19...Ne3+ and 19...Nf2+) are clearly decisive:
( [Stockfish 10 64] 34:-9.98 19...Rxe4 20.Nxe4 Ne3+ 21.Kg1 Qxe2 22.Qe6 Nd1 23.Rxd1 Qxd1+ 24.Kg2 f3+ 25.Kh3 Qxh1 26.b6 axb6 27.Nxd6 cxd6 28.Kg4 Qxh2 29.Qe7 Rg8 30.Kxf3 Qh1+ 31.Kg4 h5+ 32.Kg5 Qf3 33.Qd7 Qxf2 34.Qxd6 Ra8 35.Kg6 Qe2 36.Qd5 Qe8+ 37.Qf7 Qxf7+ 38.Kxf7 Rxa2 39.Kg6 Rg2 40.Kf5 Rxg3 41.Ke4 Rg4+ 42.Kf3 Kh7 43.Kf2 )
( [Stockfish 10 64] 33:-8.75 19...Nxf2 20.Kxf2 fxg3+ 21.Ke1 Bf4 22.Qd5 Bxc1 23.Nf7+ Qxf7 24.Qxf7 Rxf7 25.hxg3 Ref8 26.a4 Be3 27.Nd2 Bf2+ 28.Kd1 Bxg3 29.Kc2 Rf2 30.Kd1 Kg8 31.Nb3 Bd6 32.Rh5 R2f5 33.Rxf5 Rxf5 34.Nxd4 Rf1+ 35.Kc2 Ra1 36.Nf5 Rxa4 37.Nxd6 cxd6 38.Kb3 Ra5 39.Kb4 )
( [Stockfish 10 64] 33:-8.67 19...Ne3+ 20.fxe3 Qxe2+ 21.Kh3 Qh5+ 22.Kg2 f3+ 23.Kg1 dxe3 24.Qd1 Rxe4 25.Nxe4 Qh3 26.Qf1 f2+ 27.Nxf2 exf2+ 28.Qxf2 Rxf2 29.Kxf2 Qf5+ 30.Ke2 Qe5+ 31.Kf3 Qd5+ 32.Kg4 g6 33.Kh3 Qe6+ 34.Kg2 Qxa2+ 35.Kh3 Qe6+ 36.Kg2 Qd5+ 37.Kh3 Qf5+ 38.Kg2 Qxd3 39.Rce1 Qd5+ 40.Kh3 Qxb5 41.Rhf1 h5 42.Rf3 g5 43.Rfe3 Kg7 44.Kg2 g4 45.Re7+ Bxe7 46.Rxe7+ Kg6 )
My pick was 19...Ne3+ -+.
P.S. So where did White go wrong? Stockfish 10 indicates the decisive error was 17. Nfg5, allowing 17...Bxg2 18. Kxg2 Ng4! -+ (-3.57 @ 29 ply).
Instead, Stockfish 10 recommends complicating with 17. Qc4 fxg3 ∓ (-1.59 @ 34 ply). However, 17. Qc4 is a computer move that is difficult to see over the board and even with best play may not assure White's survival.
For an earlier improvement, instead of 11. Rac1 f4! ⩱ to ∓ (-0.69 @ 28 ply, Stockfish 10), White can counter Black's flank attack and maintain a positional advantage by taking action to stengthen the Queen-side and the center with 11. b5 Nb8 12. e3 ⩲ (+0.76 @ 30 ply, Stockfish 10).