A rather dubious idea. White does much better with either 5.O-O or 5.Qe2. The latter move is most forcing, and after 5.Qe2 d5! (5....d6? 6.e5 dxe5 7.Nxe5 Be6 8.Nxf7! Qe7 9.Qxe6 1-0 Akos--Csaszar, Hungary 1968) 6.exd5+ Be7 (6....Qe7?! 7.Ne5 Nbd7 8.f4! +=) 7.c3! (Better than the superficially attractive 7.Bb5+?! Kf8! 8.O-O a6! 9.Bd3 Nxd5 =+) 7....Nxd5 8.cxd5 White has a slight edge.
Really the only way to protect the f-pawn from attack. But this move is quite strong because it practically forces White to exchange by 6.exd5, after which he will have trouble protecting the pawn at d5.
Not 6....Qe7? 7.O-O! and suddenly White is better. The Bishop develops with attack on the Knight, and Black threatens to castle or play ....a6, after which he will have the better game due to the strong Black center pawns and the weak White pawn at d5.
White seeks to exchange pieces, hoping that a position with reduced material (and no Queens, after 9....Qe7 10.Bxd7+ Kxd7 11.Qxe7+ Kxe7 11.c4 =) will bring some relief. Black, however, will have none of that. Though he surrenders the right to castle by moving his King, he avoids the exchange of Queens. He also clears the e-file for an attack with his Rook at a8, puts his King in a safe place, and renews the pressure on d5. And due to Black's control of the center, the King is quite happy at f8.
White was faced with a difficult choice: he must either surrender his d5 pawn (11.O-O Nxd5) or give up the right to castle. He seems to have chosen the greater of two evils, as the sequel will show. But at least he avoids 11.c4? Re8 when the pin along the e-file costs him at least a piece.
Threatening 13....Qg4 to exchange off Queens, after which the pawn at d5 must eventually fall. The pawn advance will also free Black's Rook at h8 after a further advance to h4. Once the Rook is in the game, Black will have an overwhelming position.
Exchanging by 14....dxc3 15.Nxc3 only helps White to develop. Now Black begins an attack using his superior forces. Notice that White has yet to move any of his queenside pieces, which means he will have fewer defenders than Black has attackers.
White seeks exchanges to blunt Black's attack. But the Rook exchange leaves White's back rank unprotected. It is difficult to suggest a better idea though, and no better was 15.Bf4? Bxf4 16.Qxf4 Rf5 17.Qd2 Ne4 winning at least the exchange and a pawn.
White's King has shifted to the kingside, and Black's attack has followed. The Knight maneuver has weakened the dark squares in White's fortress, allowing the Bishop to penetrate. If now 21.Qxf5? Bg3+ 22.Kf1 Qe8#.
To protect his King, White finally must surrender the d-pawn, which he had chosen to protect at the cost of King safety. Clearly he would have been better off castling at move 11.
Though it has cost him a pawn, White has finally developed his forces. But it is too late, as Black's attack finally breaks through to victory.
The h-pawn is unstoppable. White desperately now tries for a perpetual check, but Black has calculated that his King will be able to escape to the kingside, where it will be protected by two Queens!
With an extra Queen, Black should have no trouble checkmating White's wandering King. This was the final game of the tournament, and Santasiere bragged that he used only 10 minutes of his own time to play it! The capping combination is quite attractive.