Bathroom and meal breaks are permitted :P
I think, for around 35 hours and then one night sleep and continued the next day.
I do it a lot, which is why i am looking for a gamer girl who wanna do the same, like having a game marathon that last for hours and hours.
I am sure i've done a lot of longer ones, but it's so often i've unsure on how many hours i've really played.
But every new game that comes out, i don't stop playing them until i am finished with the game