Gypsy: <26.Bf4> Somehere soon after this move must be the genesis of Hort's ambush/trap. White seems to have retained most or all of his opening advantage and clearly now aims to brute-force Rc7, with decisive effects.
<28...Bxg4!?> From here on, I believe, Hort is already setting up the ambush.
<29.hxg4 Bxd6 30.Qxd6 a5> A forcing sequence that looks inocent enough.
<31.Rc1> White seems to suspect nothing.
<31...h6(!)> The trap mechanism is already in place. But Black has to loose a tempo without raising suspicion. As this opens up useful luft
for Black king in the most natural fashion, this was the perfect move fro the task at hand.
<32.Rc7?> White seems to smell blod. But preparatory 32.g3 was
the way to go.
<32...Qc8!> A pin so terrible and yet so feeeble-looking.
<33.Qd7?> A great moment of the game -- both players certain that they are winning! White has now stepped fully into the ambushed ravine. Either 33.Kh2 or 33.Qg3 would have avoided the immediate disaster. But, in either case, Black seems to be fine after 33...Re4.
<33...Re1+! 34.Kh2 Rc1!> The trap mechanism of the ambush went off. Polugaevsky should have resigned right here.
Of course, all of this is just a "world according to Gypsy". I do not realy know when Hort noticed the trap possibility, I am just learning to read the "forensic" reccord. There probably was a time-presure; not only Polu missed the tactic, but he kept on playing even after the trap went off.