Originally posted by jonrothwell
That was the original line i wanted to get to work. To prove that the open file would be lethal for black since he was unable to castle quickly enough.
Kd8 is forced because of the pretty double knight checkmate, but white needs to play Qc1 before Nc6+. The idea being that either you will win the queen, Be7?? Nc6+ Nb4+ Nxa2, or threaten checkmate with Nc6+ Kxc7 Na7+ Kb2 Qxc8+ Kxa7 and the bishops & queen combination should win one of the black knight and then mate.
The only problem is that after Qc1 black can play Nc5, blocking the open file. So white plays b4 to displace the knight, right? Well ...Nd7 and black loses only if he forgets that he can put his knight back on c6, with Nxe3 he counterproductively invites white to use the e-file, even Nd3 fork Qc3 Nxe1 Nc6+, white can only force perpetual (Kd7) it is black who would need to choose to helpmate (Kxc7???).
Black's position is very solid after b4 Kxc7! bxc5 exc5 Be5 (why not i guess) Kb7 and now the three connected passed pawns are dangerous.
White can of course drop his plan of all pieces on the c-file and try Nc7+, Qb1, Na8, Nxb6. after Na8 of course not ...Nd3 because of the weak c7 square. But Bb7 forces the knight to move and now the queen can no longer infiltrate on c7. White moves his knight and after the fork on d3 he is forced to trade queens and enter an endgame.
I don't think this endgame would be fun for white, he is about to be two pawns down.
Much nicer is PhySIC's suggestion keeping pawn equality and the bishop pair.
Too bad, I really liked the knight and queen attack on c7. White just needed one more tempo.