Longest Chess game
At the time this game was played, FIDE had modified the fifty-move rule to allow 100 moves to be played without a piece being captured in a rook and bishop versus rook endgame, the situation in Nikolić versus Arsović. FIDE has since rescinded that modification to the rule.
The longest decisive tournament game is Fressinet–Kosteniuk, Villandry 2007, which Kosteniuk won in 237 moves. The last 116 moves were a rook and bishop versus rook ending, as in Nikolić – Arsović. Fressinet could have claimed a draw under the fifty-move rule, but did not do so since neither player was keeping score, it being a rapid chess game. Earlier in the tournament, Korchnoi had successfully invoked the rule to claim a draw against Fressinet; the arbiters overruled Fressinet’s argument that Korchnoi could not do so without keeping score. Fressinet, apparently wanting to be consistent, did not try to claim a draw against Kosteniuk in the same situation.