To give it it's full title; Warhammer: End Times – Vermintide henceforth known as just Vermintide because no one needs two subtitles is a coop first person melee game in a similar style to Left 4 Dead but instead of chatty survivors and boring old zombies it has fantasy races and literal tides of vermin thanks to the Skaven. The above video also has a part two linked in its description on YouTube if you can't get enough of game information interspersed with rat-men getting their heads staved in in dark rainy environments.