I would like to organize a game playing session for 140 people in the same room. I could just split them up into lots of small groups and organize a tournament. But then I started to wonder, are there any massively multiplayer non-online games? My restriction is that any material needed will have to be printed out.
The only massive group game I can think of is Ultimate Werewolf, which plays up to 68 players. With that amount of people, you'll want at least two moderators each. You can split your 140-person party into two large groups with a copy of the game each.
One game that could accommodate that number of players (provided you were willing to break the individuals up into multiple teams would be a Wits and Wagers style trivia game). If you broke into 10 person teams, you would have 14 teams. Wits and Wagers is a trivia game where the answers are all numeric (or dates).
What I believe makes Wits and Wagers work for this setting is the fact that the questions aren’t necessarily something you would expect people to know (ex. How many stairs in the Empire State Building?). As such, it is easier for a team to throw out different answers and try to find the one that the team agrees sounds like it might be correct. You can then compare the answers from all teams and determine a winner. The goal of each question is to get the closest without going over.
If you were to use the Wits and Wagers questions, my recommendation would be to ignore the betting portion of the game where all the answers are lined up in numerical order and players place up to two bets on the answers that they think are correct (with players allowed to bet on answers besides their own). I think if you tried to include the betting portion, it would really slow down the game to a crawl and you’d struggle to get through multiple rounds. Instead, I would run it simply as a game where the first team to some number of points (5? 10? Really depends how long you want this to go on).
From the set of Wits and Wagers games, the one that might work best as is in this setting is Wits and Wagers Family. I've not actually played this version however, but it sounds like it could work if you wanted to give teams the option on betting on others guesses.