I couldn't possibly begin to explain to someone not interested in chess the impact Bobby Fischer had on the game when in 1972 he defeated Boris Spassky to become champion of a game the Soviet Union had made their own at the height of the cold war, so I will have to point you to this article which will give you a flavour.
He never defended his single world title in protest at the nature of the chess tournaments were played, leading to a never-ending battle between Karpov and Kasparov in 1986 when his ideas were finally adopted and nearly bankrupted FIDE, the World Chess Federation.
In 1992 he came back defying US sporting sanctions against Yugoslavia, defeating his nemesis Spassky 10-5. He spent the final years of his life in Japan before taking citizenship of the nation which hosted the 1972 match, Iceland, to avoid extradition to the US in 2005. He spent some of this time praising the September 11 attacks and making the odd anti-Semitic remark despite being of Jewish parentage. Rabid anti-Americanism seemed to have replaced his rabid anti-communism.
There is a fine line between genius and madness, and I think we can safely say that Fischer straddled both worlds.