That makes this easier. PVP isn't new of course, the Romans had the coliseum, and duels to the death used to be a valid way to solve an argument. Either way, that's what this scenario aims to be, though it has a few more bells and whistles.

He wants us to murder each other, for reasons which I'm sure benefit him. Money, fame, maybe he needs materials from our deaths for a ritual, or maybe just plain entertainment. So far we've been a united front, since he's done nothing for us, and the promise of escape really doesn't hold much water without proof. But that's just one way he can move us, and there are plenty others.

All in all, there are many ways to play this scenario but there are two distinct ways of looking at it. The first: this is us versus him, PVE. The second: this is me versus everyone else, PVP. They each have their pros and cons, of course. But most people, including me, are far more familiar with PVE. It's human natured to band together and fight for survival, no matter the situation. Except...even if twenty-four of us decide to play PVE, if only one person decides to go PVP? It shakes everything up entirely, and it'll likely be a cascading effect after that.

Above all, it's important to know what kind of game you're playing.