1.d4 Nf6 2.Nf3 g6 3.c4 Bg7 4.Nc3 d5 5.cxd5 Nxd5 6.e4 Nxc3 7.bxc3 c5 8.Bc4? Transposing into a line in which White's knight belongs on e2 rather than f3, so as to meet ...Bg4 with f2-f3. White should prefer 8.Rb1, 8.Be3 or 8.Bb5+.
8...0-0 9.0-0 Nc6 10.Be3 Bg4 11.e5 Qc7 12.Rc1 Rad8 13.h3? Missing Black's threat. 13.Qe2 was reasonable, defending the bishop on c4.
13...Nxe5! 14.Be2 White must lose a pawn. The knight is immune, and if 14.hxg4 Nxc4. Alternatively 14.Bxf7+ Rxf7 15.hxg4 Nxg4 (threatening ...Rxf3) 16.Re1 Nxe3 17.fxe3, and Black stands well.
14...Nxf3+ 15.Bxf3 Bxf3 16.Qxf3 cxd4 17.Bxd4 Bxd4 Not bad, but 17...e5 18.Be3 f5 is better. In a heavy-piece ending, one or even two extra pawns may not be all that important, given the possibility of mates and perpetual checks.
18.cxd4 Qd7 19.Rfe1 Rc8 20.Rxc8 Rxc8 21.Qa3 Qxd4 22.Qxe7 Better was 22.Rxe7, preventing ...Rc2 due to 23.Re8+ Kg7 24.Qf8+ Kf6 25.Qh8+.
22...Rc2 23.Re3 Qa1+ Tempting, but this moves the queen from her dominant central post. The simple 23.Rxa2 was preferable.
24.Kh2 Rxf2? This nets another pawn and defends f7, but in fact it allows White to force an immediate draw. Black needed to try 24...h5, e.g. 25.Qxb7 Rxa2 26.Re8+ Kg7 27.Qe7 Rxf2.
25.Qd8+? White misses the saving move, which is admittedly very hard to find over the board, namely 25.Qc5!! when the subsequent Re8(+) will give an attack sufficient to force perpetual check.
25...Kg7 26.Re8 Qf6 27.Rg8+ Kh6 28.Qf8+ Kh5 28...Kg5 is better, since Black's pawns will not be weakened.
29.Qc5+ Qf5 30.Qxf5+ gxf5 31.Rb8 b6 0-1