My record is a lan party in which we FINISHED an EIGHT! player game of sins of a solar empire. Eight player Free for all.
For those of you who have played the game you understand how long it takes.
For those of you who do not a game where me and my friend started right next to each other went for 4 hours. In this game we were all at least 30 mins travel away from each other at the beginning.
To clarify the game lasted for a total of 46 hours of gameplay. Much energy drink was had.