Efim Geller was one of the few Grandmasters (Tal and Janosevic being the other two) to have a winning record against Bobby Fischer. In this, their final encounter, Fischer may not have evened the score, but he certainly got some measure of revenge.
The game is one of Fischer's famous grinds, the ending of which has been published many times, but the full score, very rarely. Despite Geller's 15. c4, which blundered away a Pawn, the game was a dead draw, almost from the opening move, but still Fischer kept grinding and grinding, trying to get something out of the ending. By Move 25, it was a drawn 4 Pawns vs. 3 (all on the same side) Rook ending. Still, Fischer kept grinding. The simple 66. Kg3 was a simple drawing move that virtually anyone would have seen, but Geller, exhausted, had a hallucination. After 67. Kxf5, he believed that Black couldn't play 67... g3 because of 68. fxg3+, and 69 Kxf1!! (imagining that his King moved like a Queen). The hallucination is contagious, because I've seen more than one annotator swearing that the more they look at the position, the more they imagine that 68. fxg3+ and 69. Kxf1 are possible too!
However, even this still wasn't enough to lose the game, and required more help on Geller's part. 71. Rd8 Ra6+, 72. Ke4 would have allowed White to give up his Rook for Black's last pawn, then forcing Black to do the same. 71. Ke6 would have worked also. Instead, Geller played the incomprehensible 71. Ke5, and managed to lose! Any resemblance to chess at the end is purely coincidental.