So it's a massively multi-player co-op game instead of PvP?
I don't know enough about gaming to say, but I'd assume "co-op" means cooperative. Yet the premise here is that there's a single victor at the end, so they must be competing in some way. Is there a way for a single player to win a co-op game?
What I wonder about a game based on saving people from monsters is, did the game designers merely choose to build the game around an existing monster threat, or did they create the monster threat for the sake of the game? I bet the Riders initially think it's the former until there's a Shocking Revelation that it's the latter and the game runners are evil.
Or it could be something like Blade's approach where the game has an ancient origin and was restarted by accident, and there's no choice but to play it out.