https://motherboard.vice.com/en_us/article/evme5w/vermintide-2-review

In 2008, developer Valve published Left 4 Dead, a cooperative multiplayer game where groups of four players moved through post-apocalyptic cities, fending off hordes of zombies controlled by an "AI director." There were only half a dozen maps, but the AI switched up where and what kind of enemies appeared at different times to heighten the drama. It was never the same game twice. A year later, Valve released a sequel, but it hasn’t touched Left 4 Dead since.

It was a unique experience. It was impossible to cut through the zombie hordes alone and teams that didn’t work well together failed. Left 4 Dead 2 is one of my favorite multiplayer games of all time, and almost 10 years after it first came out I’ve still to find anything that scratched the same itch, though many games tried. Then I found Warhammer: Vermintide and its superior sequel Warhammer: Vermintide II, which was just released last week.