Longest Single Session
This one's not ambiguous at all, and the answer is about 60 hours. Yes...60 hours of continuous gaming through a single open ended exploration of a setting.
I don't know about other parts of the world, but in Australia we have things called "Long Weekends", they occur when a public holiday Monday happens (most of our public holidays occur on some particular monday of the month, and in the old days when a public holiday was designated on a specific date, the actual day taken as a holiday was shifted to a Monday).
The marathon session occurred back when I was young and had energy. I didn't have university on the Friday, so I slept and prepared a concoction of cola, coffee and a vitamin pill called 'berocca'... it tasted awful, but this "wake-up juice" was something we used to get through all-nighter assignments. I made three two-litre bottles of the stuff. It was fully legal, and when another friend made sure to bring along some 'No-Doz' tablets there was no chance we'd sleep for a few days.
The premise was simple. Old late 1990s World of Darkness, Sabbat/Black Hand - Mummies - Hunters. Gaming was interspersed with snacks and occasional meals, but even over food we'd be discussing where to head next and reflecting on the story so far.
A group of monster hunters had been sent to Peru to investigate something big going down.
Act 1 (Friday night, 6pm to 4am) - The first 10 hours involved exploration of Lima and Cuzco...where they found Sabbat and Incan Mummies warring in the streets.
Act 2 (Saturday morning, 4am to noon) - The next 8 hours involved discovering that the characters were no match for these supernaturals and they'd need a quick power boost from the Vampires. These players knew nothing about the Sabbat or the Hand (neither did their characters), being incredibly useful to the vampires, they were offered a variety of potential sires (as long as they could successfully convince such a sire to embrace them). Act 2 ended with an embrace by a vampire of 5th to 7th generation.
Act 3 (Saturday afternoon/evening, noon to midnight) - The next 12 hours saw a rapid accumulation of power as potent blood infised their souls and they mastered the basic arts of their disciplines through various scenes.
Act 4 (Sunday morning, midnight to 10am) - The next ten hours saw the characters begin to understand the "devil's deal" that they had made as former allies begin to turn on them, and the supernatural forces of the area ramp up.
Act 5 (Sunday afternoon/evening, 10am to 8pm) - One by one the original vampires are taken down, or choose to leave the region because it's just getting too dangerous. The player' don't get the hint, and think that their mix of high technology and vampiric disciplines should be able to take down the Incan Mummies where the antiquated tactics of the elder vampires have failed. There are a series of wins and losses through this part of the game.
Act 6 (Sunday night/monday morning, 8pm to 8am) - There was no single climactoc battle, but instead a series of running battles between the vampiric PCs, the mummies and their former allies. The biggest battle started at the stroke of midnight, and lasted a few hours. The PCs had to specifically finish off the Incan mummies before the next sunrise, when they would have to resist falling into torpor while the Mummies would gain renewed energy from the sun. I rememberfudging die rolls to allow PCs to survive at this point, and granting bonuses for awesome stunts and descriptions, but one by one fatigue had started hitting players. As soon as a player fell asleep, their character was killed off. By the time the red disk of the sun crested the horizon at about 5.30, three of the six player's were awake, with their character's severely injured but still active. The remai der of the time was spent describing how the team cleaned up the most heinous damage to the city, and establishing how the characters would turn the city into their own territory for an ongoing campaign.
By about 8am, we finished off with breakfast, then slept for the rest of Monday.
The rest of that campaign never happened, the players involved just never managed to get time off together, and we all just drifted our separate ways.