21... Rxf7 suggests itself, but White has 22. Rxf7 Qd8 23. Bg5 Qc7 24. Qf4 and the g4 knight is trapped.

If you had planned this, I would have said it was a fine finesse, instead of 25.Bh6+!? at once. The reason is that Black has very few options: the text move, and this: 25.(Bg5!) Nf6?26.Bxf6+ and [A] 26...Qxf6 27.Qh6+ Kg8 28.Ng5+ and mate next, or [B] 26...Kxf6 27.Rf1+ Kg7 - not 27...Bf5 28.Rxf5 gxf5 29.Qg5# - 28.Qh6+ Kg8 29.Nd8+!! (29.Ne5+ also wins but not as quickly) and 29...Kh8 30.Rxf8+ Qxf8 31.Qxf8# or 29...Be6 30.Bxe6+ Kh8 31.Rxf8+ etc.

The alternative, 26...Kg8, is just as horrible. Really, White has a tremendous attack here. If 26...Kg8, the best that Black can hope for is to lose his queen: 27.Nxd6+ Kh8 28.Nxe8 Bxh6 29.Qd3. It is true Black gets a counterattack by 29...Be3+ 30.Kf1 Rxe8 31.h3 Rf8+, but White can weather it: 32.Ke2 Rf2+ 33.Ke1 and Black runs out of attack (33...Rd2 34.Qxd2). White could go for the simpler line, settling for a mere two-pawn plus: 27.Nxd6+ Kh8 28.Nxe8 Bxh6 29.Qxh6?! Nxh6 30.Nf6 - a smaller advantage to White than in the other line, but Black has correspondingly fewer prospects of counterplay.

Black could have tried the last-ditch 28...Bf5 and survived a bit longer: 29.Rxf5+ Ke7 30.Qh7 gxf5 31.Ne5+ Kd8 32.Nc6+ Kc8 33.Qa7 Rb7 34.Qa8+ but must lose at least the queen. The annotator possibly underestimates just how strong an attack he had one the "windmill" was set up. After that Black had scarcely a prayer.

Excellent attacking options once you got the windmill set up. Black never really has a chance

Windmills are usually performed with rooks, and usually in endgames - this annotation has proved that a middlegame knight windmill can be effective, not only in gobbling up loads of material and gaining an easily won position, but in performing a neat checkmating attack. Well played!!!

Very enjoyable game and comments. Thanks