patzer2: Here's my look at today's Friday puzzle (24...?) and game with the opening explorer, Deep Fritz 15 and Stockfish 8:<1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 dxc4 5. a4 Bf5> The game enters a popular mainline of the QGD slav defense (D17).
<6. e3 e6 7. Bxc4 Bb4 8. O-O O-O 9. Qe2 Bg6 10. Ne5 Nbd7 11. Nxg6 hxg6 12. Rd1 Qa5 13. h3 => (0.26 @ 27/40 depth, Stockfish 8) Though this move is seldom played at master level, the computer seems to slightly prefer it.
Other popular tries here include 13. Bd2 as in Kamsky vs Kramnik, 1995, 13. Qc2 as in Karjakin vs J Smeets, 2011 and 13. e4 as in Kasimdzhanov vs Ngoc Truongson Nguyen, 2010.
My personal preference here is 13. Na2 as in White's wins in L Dominguez vs E Najer, 2015 and
Kasimdzhanov vs A Deviatkin, 2011.
<13... e5 14. Qc2 exd4 15. Rxd4
Ne5 16. Be2 Rad8 17. f4!?> White enters complications which give
Black dangerous attacking opportunities with no risk. Instead, White can maintain calm equality with 17. Bd2 = (+0.14 @ 36 depth, Stockfish 8).
<17...Rxd4 18. fxe5 Qxe5!> This surprise move, sacrficing the Rook for an attacking position, gives Black the advantage of surprise with excellent winning chances if White makes the slightest mistake.
<19. exd4 Qxd4+ 20. Kh1 Qe5 21. Qd3 Re8 22. Bd1?> This is the decisive error. Instead, 22. Bf1 = (+0.07 @ 38 depth, Stockfish 8) gets it back to level for White after 22. Bf1 Nh5 23. Ne2 Re6 24. g3 Qc5 25. Qf3 Rf6 26. Bf4 Nxf4 27. gx4 Qc2 28. Ng3 =.
<22... Qe1+>
(-9.25 @ 30 depth,
Stockfish 8) Black is now winning.
<23. Kh2 Bc5 24. Ne2>
If 24. Qd2, then Black wins after 24...Qg1+ 25. Kg3 Bd4 26. Bf3 Be5+ 27. Kh4 Bh2 28. Ra3 Re5 29. Ne4 Nxe4 30. Bxe4 Rxe4+ 31. g4 f5 32. Qc3 Rxg4+ 33. hxg4 Qxg4#.
<24... Rxe2!!> This solves the Friday Apr 28, 2017 chessgames.com puzzle.
<25. Qxe2>
If 25. Bxe2, Black wins after 25...Bg1+ 26. Kh1 Ne4 27. Qd8+ Kh7
28. Bf1 Bb6 29. Be3 Qxe3 30. Qh4+ Kg8 31. Bc4 Bc7 32. Rd1 Ng3+ 33. Kh2 Nf5+
(mate-in-six to follow, Deep Fritz 15)
If 25. Qd8+, Black wins after 25...Kh7 26. Bxe2 (26. Be3 Ng4+ 27. hxg4 Bd6+ 28. Qxd6 Qh4+ 29. Kg1
Re1#) 26... Bg1+ 27. Kh1 Bf2+ 28. Bf1 Qxf1+ 29. Kh2 Qg1#.
<25... Ng4+ 26. Qxg4 Bg1+ 0-1> White resigns as it's mate-in-two with 27. Kh1 Bf2+ 28. Kh2 Qg1#.