In the movie The Wild Hunt, after a series of incidents occur with Evelyn, the shaman's followers end up kidnapping her and make her wear the skull mask. After she puts on the skull mask she starts freaking out and runs off. They start following her, starting the Wild Hunt, but instead of playing in-game they actually start killing people.
Why did Murtagh and his followers start killing people? Being upset over what happened in a game seems like a rather odd issue to kill people over.