We all know Gary is top 1 or 2 all time, but 17 Rxb7 is an astounding move. The fact that he follows that up to beat Shirov (no slouch himself)based solely on a slight development advantage and better pawns is amazing while giving up a whole exchange.
I had just checked this game out on a Youtube video the other day. The commenter stated that the exchange sac was for total domination of d5 with the white knight and the follow up b4 to keep the black knight off c5. Kaparov's games fascinate me but I can't do that kind of stuff.