One of the sharpest lines in the entire Karo-Cann opening Black can choose.
Natural square for the bishop but perhaps it can work better from another square.
6. c3 Bf5 7. Nf3 e6 8. g3 is considered to be optimal set-up for White. Here Rg8 is not dangerous any more and Nh4 might come. If Black goes with Be4 and f5 then Ng5 could be very dangerous like in next instructive game: 8… Bd6 9. Bg2 Be4 10. 0-0 Nd7 11. Re1 f5 12. Ng5! Bxg2 (12… Bd5 13. Qh5 Qe7 14. Bxd5 cxd5 15. Rxe6+-) 13. Qh5! 1-0 in Wells,P (2490)-Nestorovic,V (2290) Harkany 1994
6… Bf5 7. Ne2 e6 8. Ng3 Bg6 9. h4 h5
The knight looks excellent on f4, attacking both Bg6 and pawn h5 but this maneuver costs two moves.
White holds small but stable advantage with 10. c3 Bd6 11. Qf3 Nd7 12. Bf4 Bxf4 13. Qxf4 Qb6 14. 0-0-0 0-0-0
10… Bd6 11. Nf4
11… Be4! saves pawn h5 because pawn g2 hangs as well. If 12. 0-0?! Nd7 13. Nxh5?! f5 Black`s attack worths more than a pawn.
White could immediately take 12. Nxh5 because if 12… Bxc2 13. Ng7+ Kf8 14. Nxe6+
12… Nd7 13. Nxh5
Really strong is 14… Qb6! It attacks pawn b2, threat is Qb4+ so to take Bc4 as well… and keeps option for Bxf4 and then Rxg2
15. Qd2 0-0-0 16. 0-0-0
Perhaps the key moment of the game: where to go with the bishop?
The most principled move – here bishop protects the pawn.
But trouble is that Black gets too much counter play 17. Bd3 Bxd3 18. Nxd3 Rxg2 does not look very promising for White 19. Qe2 f5
It was really difficult to spot that after 17. Bb3 Bxf4 (17… e5 18. Qa5!? motive easy to miss during the game) 18. Bxf4 e5 19. Be3 (19. Bg3 c5!) 19… Rxg2 (19… c5 20. Qa5 Again, so if cxd4 21 Bxd4) 20. Qe1! White has better position (20. Qe2 Bg4)
Even stronger is 17… c5 because bad is 18. dxc5? Bxf4 19. cxb6 (19. Bxf4 Rxd2 20. Bxc7 Rxc2+ wins) 19… Rxd2 20. bxc7 Rxc2+ 21. Kb1 Rxf2+ with victory.
19. Bxd4 Bg4
No good is 19… Bg4 20. Nxf6
20. Be2 Bg6
Moving from Bf4 in case. Of course not 21. Nxf6?? Rxh6-+
Fine bringing the piece closer to the opponent king.
The engine gives 21… d3! 22. cxd3 Nc4 23. Qc1 Nxb2 24. Qxb2 Rxh6 Black has clear advantage regarding the exposed White`s king.
Attractive distraction (although White still can hold the position) of the queen from task of defending the king.
Direct 22… Qb6 23. Ka1 Nb4! works excellent, for example 24. Bd3 Rxh6! 25. Qxh6 Qa5 26. a3 Nxd3 27. cxd3 Bxa3! 28. bxa3 Qxa3+ 29. Kb1 Rd5 creates a mating net.
23. Qxh6 Bf4 24. Qg7 Qb6
Amazing that after 25. Bd3 Nc3+ 26. Ka1 Qa5 (26… Nxd1 27. Rxd1 is worse for Black) 27. bxc3 Qxc3+ 28. Kb1 Qb4+ it is perpetual check on the board… such a big chess fight could finish peaceful!
White`s chance to save the game was 26. Bd3! Bxd1 (26… Bxd3!? 27. Rxd3 c5 is also very interesting) 27. Rxd1 with objectively better position for Black but with a quite demanding task of proving it.
26… d3 27. Bg4+ Kb8 28. Rde1 d2
If White can play Qd7 now (threatening Qc8 too) that will be victory for him. Unfortunately, no time for that move.
After 30. Rxd8+ Qxd8 31. h5 Qa5!
(In the game of chess one mistake can ruin everything: 31… Qb6?? 32. Qe8+ Kc7 33. Qd7+ Kb8 34. Qc8#)
32. Qe8+ Kc7 33. Qc8+ Kb6 34. Qd8+ Nc7 it is not possible to prevent well Black`s threat Qc3!!