They have a unique mod based on Killing Floor's IDRPGMod running in KF2.
Playing this Server makes a LOT OF FUN!
Check it out if you are interested:

Steam Group:
https://steamproxy.net/groups/MadHouse-MG

Discord:
https://discord.gg/bXQPxNv

Server information:
62.210.172.72:7777 - EASY (0~800)
62.210.172.72:7778 - MEDIUM (100~1800)
62.210.172.72:7779 - HARD (800~4000)
62.210.172.72:7780 - EXTREME (1500+)
62.210.172.72:7781 - INSANE (3000+)