dzechiel: White it play. "Very Difficult". Material even. White's pieces are poised to assault the castled black king. Candidate moves are:
- 18 Bxh6
- 18 Nf5
- 18 Bg5
- 18 Ng6
- 18 Qg6
There are others, but they don't seem as forcing. A big concern of mine is the bishop on b3. This piece seems to be key in hold black's f-pawn in place. Should black have a chance to play ...Nxb3, our attack would likely wither. So our moves must be at least a little "forcing" to stop that move.
Note also that the black queen must keep an eye on f7 to stop Bxf7+ picking up an exchange or Qxf7+ leading to mate in many variations.
The more I look at it, the more I like
This attacks the black queen (forcing) and is immune to capture by the queen (18...Qxg5 19 Qxf7+ Kh7 20 Qg8#) because it abandons protection of f7. It also cannot be taken by the h-pawn (18...hxg5 19 Ng6 and 20 Qh8#). What's black's response? He must maintain protection of f7 so
Time to bring in fresh troops! How about
Threatening the queen (who cannot move as this will abandon f7). That means
So far our moves have been forcing enough. Let's try to keep the pressure on with
I hope this is right. It's not nearly as forcing as our previous moves, but it does have threats. Black has a couple of replies:
First, let's consider the capture. After
white can play
21 Qg6+ Kh8 22 Qxh6+ Kg8 23 Qg6+ Kh8 24 Bxf7
threatening mate with 25 Qh6#. The only way I see to stop this is 24...Bf8 or 24...Qxf7, but these both give up the queen (we took the pawn with check on move 22 rather than the bishop capture in case black does want to go for this line, we have an extra pawn) and white should win easily.
So I think the second line is key, let's look at
white ignores the capture and responds
threatening 22 Qh8#. If
21...Kxg7 22 Nf5+ Kf6 (22...Kf8 or 22...Kg8 allow a queen check on g5 or h6 and mate next move) 23 Qg4+ Ke6 (23...Kg6 24 Qh6#) 24 Ng7#.
Wow, this required some serious visualization. I really hope I'm right, 'cause I'm not looking any more. Time to check.