The Dark Horse (2014)
This is a New Zealand movie about a chess-player with a grand name Genesis Potini, who is known for creating a chess school for underprivileged kids. He was a speed chess player, and we was suffering from bipolar disorder. And not some weak shit disorder either, like people boast about these days, he had fits that landed him into mental hospital on few occasions. Despite his problems, he took on teaching, and in just few weeks time trained one of his students to become a winner of the local Youth Championship.
So, how true? Honestly, I can't say. The most I found is this article, and it's not even on any movie or historical site, it's on a chess site. Still. Basic outline is true - guy is crazy, guy takes on teaching chess club, guy leads his club to victory in a shortest time. Drama stuff? I'd say, it's Hollywood, but truth is, stuff like that could have been happening left and right there at the time, so that dramatization might not have been too far off.
Interesting is that some stuff isn't even in the movie. Apparently, Gen took on teaching kids with disorders, like ADHD and stuffs. And got some results, contributing to spheres of research that try to cure those conditions. He was really obsessed, even more than it is shown in the movie, with chess. He was, apparently, more violent, than it is shown...
Sooo... basic outline is true, but particulars are more of a fiction, and some of the interesting stuff wasn't covered. Also, I will say this right now - it's more of a human drama movie, than a movie about chess. Doesn't make it worse, but I did have to make that warning.