Woody Wood Pusher: I am analysing this game and after 26...f6 the storm brewing on the horizon is not just an optical effect, Master Chess (32 bit 20 MHz) evaluates the position as +2.8.
White could even play 30. Qxd6, Rxd6 31. Rxg7+, Kf8 32. Rxb7 and still have a winning advantage, although harder to convert. 30. f7+ is a master stroke though and black probably had not expected it.
After 30. f7+, Bxf7 31 Qxg7 is mate
30...Kf8 31. Qxg7 + leads to mate 31...Ke7 32.f8=Q mate
After 30..Kxf7 black cannot avoid mate or massive material loss
e.g. 32...Qf8 33. Re4+, Re7 34. Rxe7+, Kxe7 35. Bc5+ picks up the queen.
32...Ke7 33 Re4+, Be6 (mate in 8!) 34 f6!, Kf7 35 Qg7+, Ke8 36. Qg8+, Qf8 37. Rxe6+, Kd8 38. Qxf8+, Kc7 39.Qc5+, Kb8 40. Rg8+, Nc8 41 Qxc8 Mate
what a beautiful mate that would have been! The white f-pawns are the heroes of the game!