Nintendo

5

It took Piotr Kusielczuk 91 hours to beat Miracle Piano Teaching System, an NES game created to teach kids how to play the piano. (To pull it off, he had to teach himself how to play piano.) That was the longest. He's also spent 39 hours with the billiards game Championship Pool, 37 and a half hours with the shoot'em-up Ikari Warriors, and more than 16 hours playing Q*Bert.