The Big John was originally an amusement park robot, but its control was taken over by the Amadeus Syndicate and converted to a weapon, turning everyone in the park into zombies or mummies using a virus similar to what the purple gas and The Ten Commandments of Moses used. It tries to turn the player into a zombie which, if successful, could end up being its undoing, as this opens up the possibility for the player to attack via the powerful virus vial "grenade".