Link: https://store.steampowered.com/app/1250/Killing_Floor/

Killing Floor is a cooperative survival horror shooter with a first-person view, which takes place on the streets of abandoned cities and suburbs of Britain shortly after an unsuccessful experiment on creating and cloning "super-soldiers". You and your comrades - members of the armed forces, dropped into these places with the simple task - to survive as long as possible, clearing the landing zone from the effects of a failed experiment!
 
Cooperative gameplay - six players versus countless mutants
 
The system of improvements that allows you to use online achievements to improve the skills of the hero
 
More than 170 achievements, such as Respect for Death, awarded for killing 10 monsters devouring the corpses of your teammates or Hot Fun for killing 25 burning monsters from a crossbow
 
The “ZEDtime” time dilation function that allows you to see game moments in detail even in multiplayer
 
Single game mode "in one"
 
Ten types of monsters, concerned only with tearing off your head. In addition to jaws and claws, these offspring can be armed with chainsaws, machine guns or even a grenade launcher
 
Wide, with more than thirty-three types of weapons, the choice of weapons - from knives and fire ax to shotgun, rifles and flamethrower
 
Welding, medical devices and armor designed to facilitate survival
 
System improvements. You can choose those that will help you resist the countless crowds of mutants or will be useful to your team.
 
Open, non-linear game world: you are free to choose where and when to fight or retreat. Brew doors to make monsters go around the narrow corridors
 
Full customization that allows players to change the difficulty level, the number of waves, or even exhibit their own, made up of favorite monsters
 
Support for Steam and Steamworks functionality
 
A set of materials for creating new levels and mods