The position after 23...fxg6:

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In the position above, White made a fantastic winning move. Note that even after 24. ♘f3?! ⩲ White still stands slightly better.

In the position above, Black needs only 2 moves: ♘c7-d5-f4 and Black is fine.

If in the present position, it is Black to move, then White still stands slightly better ( ⩲) and Black's only move is ♔f7.

If in the present position, it is White to move and Black's knight ♘/c7 stands ♘/f4 instead, then Black stands slightly better ( ⩱) and White's only move is ♔b1.

In the game, the centre was closed, White castled 0-0-0 and started a king attack on the kingside. Black helped to open the files on the kingside.

Black's plan was good but too slowly:

♘c4; dxc4; c6; ♘b8-a6-c7-d5

Moreover, Black lost a tempo ♗c8-g4-f5.

The chess engine says that 3 times consecutively Black had to play c5. It is consistent with the general principles of chess strategy: if the opponent attacks on the kingside, one must be active in the centre. Moreover, opening the c-line against White's king would have been useful.

My computer analysis can be seen on Lichess:

12...h6? 13. h5 Δ 13...g5? 14. ♕d3 +-

12...h5 13. e6! Δ 13...♗xe6 14. ♗xg6! ±

My chess engine Komodo says that Black's best move is 12...♘c7 ±.

But Black still tried to hinder White's h-pawn and played

<12...♗g4?!>

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Here, 13. ♕e3 ± is a sufficiently good move. But White played

<13. h5! +->

To make such a move, White had to make some calculations, in the position shown above.

Surely,

13...gxh5?? 14. ♕d3 +-

It is also easy to calculate something like that:

13...♗xh5? 14. ♖xh5! gxh5 15. ♗xh7+! ♔xh7 16. ♘g5+

and now

16...♔g8? 17. ♕xh5 ♖e8 18. ♕xf7+ ♔h8

White can see in his calculations that he has at least the eternal check. But maybe something better, it can be checked if that position arrives on the board.

Maybe the grossmaster is able to see that

19. ♕g6! ♔g8 20. ♘e6 checkmates.

But what after

16...♔g6?

Perhaps even a grossmaster does not see a forced win in that position. Perhaps one simply evaluates the position and one's winning chances. Having some memories about similar positions. I do not know.

My analysis shows the following possible continuation:

17. ♘df3 f5

Black's only hope. Now, White has the life insurance 18. ♘e6, but better is

18. ♘h4+ ♔h6 19. ♘f7+ ♔h7 20. ♕xh5+ ♔g8 21. ♘g5! +-

Again, White has at least the eternal check, in addition, probably White can win the queen after 21...♖e8 22. ♕h7+ ♔f8 23. ♘e6+.

So White does not actually need to calculate everything till the end of the variation, which should be:

Δ 21...♖e8 22. ♕h7+ ♔f8 23. ♘g6 #

24. Qh6+

(24. Qh6+ (♕e3-h6+
♔g7-f7 ♕h6xh7+ ♔f7-e8 ♖g1xg6 ♕e6-d5 ♘h4-f5 ♖f8xf5 ♖g6-g8+ ♕d5xg8 ♕h7xg8+ ♖f5-f8 ♕g8xc4 ♔e8-d7 e5-e6+ ♘c7xe6 d4-d5 ♘e6-d8 ♖h1-h7 ♔d7-d6 ♕c4-e4 ♖f8-f7 ♖h7-h6+ ♔d6-c7 ♕e4-e5+ ♔c7-b6 ♖h6-h5 c6-c5 ♖h5-h6+ ♖f7-f6 ♖h6-h8 ♖f6-d6 ♖h8-h5 ♘d8-c6 d5xc6 ♖d6xc6 ♕e5xe7 ♖a8-c8 ♕e7-d7 ♖c6-c7 ♕d7-a4 ♖c7-c6 f2-f4 ♔b6-a7 ♕a4xa5+ ♔a7-b8 ♕a5-b5 ♖c8-c7 a2-a4 b7-b6 ♕b5-c4 ♖c7-c8) +5.78/43 202)

The position of the white pieces and the black king invites to play 24.Qh6+:

A) 24... Kxh6 25.Nf5#.

B) 24... Kg(h)8 25.Qxh7+ Kxh7 26.Nxg6+ Kg7(8) 27.Nh8+ and mate next.

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Stockfish_21033108_x64_modern:

49/78 2:23:04 +13.06 23.f4 Nd5 24.Qg3 f5 25.hxg6 h6 26.Qh3 h5 27.Qf3 Rh8 28.Rg5 Raf8 29.Rxh5 a4 30.Rh7+ Rxh7 31.gxh7 Rh8 32.Qg3+ Kf7 33.Rg1 Ke8

49/74 2:23:04 +9.07 23.Qf4 Rh8 24.Nf5+ Kf8 25.Qh6+ Ke8 26.Ng7+ Kd7 27.Nxe6 Nxe6 28.hxg6 fxg6 29.Qh3 a4 30.Rd1 Ra5 31.Qg4 h5 32.Qxg6 Nc7 33.Qg7 Rd8

49/72 2:23:04 +7.44 23.Qg5 Rg8 24.f4 Kh8 25.hxg6 fxg6 26.d5 cxd5 27.Nxg6+ Rxg6 28.Qxg6 Qxg6 29.Rxg6 Rf8 30.Rb6 Rf7 31.f5 Rxf5 32.Rxb7 Ne6 33.Rxe7 Ng5

49/66 2:23:04 +6.79 23.Qg3 Rg8 24.f4 Kh8 25.hxg6 fxg6 26.Nxg6+ Qxg6 27.Qxg6 Rxg6 28.Rxg6 Rf8 29.Rgh6 Rf7 30.f5 Kg8 31.a4 Nd5 32.Rf1 Kf8 33.Rf3 Rg7

<49/78 2:23:04 +6.36 23.hxg6 fxg6 24.Qh6+ Kf7 25.Qxh7+ Ke8 26.Rxg6 Qd5 27.Nf5 Rxf5 28.Rg8+> Qxg8 29.Qxg8+ Rf8 30.Qxc4 Kd7 31.e6+ Nxe6 32.d5 Nd8 33.Rh7 Rf7