GTFO is a 4 player action/horror cooperative first-person shooter for hardcore gamers looking for a real challenge. Players get to play as a team of prisoners, forced to explore and extract valuable artifacts from a vast underground complex that has been overrun by terrifying creatures. Gather weapons, tools, and resources to help you survive - and work to unearth the answers about your past and how to escape.
KEY FEATURES

4 player cooperative PvE gameplay that puts you and your teammates through the ultimate cooperation and communication test.
Explore a massive underground complex with a dense and dark atmosphere.
Plan your expedition, equip and operate tools, combine your firepower, communicate and coordinate as a team - every detail counts if you are to survive the nightmare.
Search the complex for information and resources to help you and your team solve your objectives and come back alive.
The Rundown: New expeditions released regularly that always replaces the old expeditions. Our goal is to invent new ways of challenging you and your teammates in new and interesting ways. You can find a video explaining the Rundown here.
Nightmarish atmosphere accompanied by music from acclaimed composer Simon Viklund.

Mature Content Description

The developers describe the content like this:

This Game may contain content not appropriate for all ages, or may not be appropriate for viewing at work: Frequent Violence or Gore, General Mature Content
System Requirements

Minimum:
Requires a 64-bit processor and operating system
OS: Windows 7 64-Bit or later
Processor: Intel Core i5 2500K or AMD equivalent
Memory: 8 GB RAM
Graphics: NVIDIA GeForce GTX 660 2 GB or AMD equivalent
DirectX: Version 11
Network: Broadband Internet connection
Storage: 15 GB available space

Recommended:
Requires a 64-bit processor and operating system
OS: Windows 10 64-Bit
Processor: Intel Core i7 4790K or AMD equivalent
Memory: 16 GB RAM
Graphics: NVIDIA GeForce GTX 970 or AMD equivalent
DirectX: Version 11
Network: Broadband Internet connection
Storage: 15 GB available space

https://store.steampowered.com/app/493520/GTFO/